It starts in Shuhada Street, which runs through what is now the settlers' security zone, the rows of empty Palestinian shops and houses boarded up with steel shutters, many daubed with Stars of David to show who is in charge here. The only permitted vehicles are those of the settlers and the Israeli military.

Shaul is seeking to demonstrate to his visitors that the settlements and the formidable military apparatus which protects them have violated the human rights of the Palestinians who live – or increasingly no longer live – in what was once the teeming Arab city centre.

But his every footstep is dogged by another religious Jew conducting a non-stop monologue designed to drown out Shaul's explanation of what his visitors are seeing. "Yehuda Shaul – he helps the Arabs," Baruch Marzel tells them, before making clear his view of the two-state peace deal with the Palestinians which the Israeli Prime Minister Ehud Olmert, US President George Bush and a majority of the Israeli public say they want. "Do you think if there is going to be an agreement that you will be allowed to pray at this tomb? Only because there are Jews living here can you visit the tomb. He isn't telling you about the 40 terrorist attacks there have been on Jews here. You can visit our Hebron centre and learn the truth about Hebron, not the lies Yehuda Shaul is filling you with."

American-born Marzel – a man to whom the term "right-wing extremist" hardly does justice – had lain in wait for the tour bus near the grave of his fellow settler Baruch Goldstein, who walked into a mosque at the tomb in 1994 with an automatic assault rifle and shot dead 29 Palestinians as they prayed. Marzel, who has a police record for attacks on Palestinians, was a prominent figure in the far right Kach group which was designated a "terrorist" organisation in both Israel and the US after issuing a

statement praising the Goldstein massacre. Seven years ago, Marzel held a macabre graveside commemoration for Goldstein, who had been lynched by enraged survivors after the attack. It was a "big party", Marzel said, to mark the anniversary of Goldstein being "murdered by the Arabs" – a somewhat incomplete account of the day in question.

Shaul struggles to conduct his tour against Marzel's noisy filibuster. At one point, Shaul walks across the street to a watching senior police officer and asks him to move Marzel on; the officer replies, "You can carry on. He's not stopping you." When Shaul then turns to Marzel himself and tells him quietly: "You are disturbing us, please can you move?" Marzel replies defiantly: "No. This my house."

This tense little scene underlines – in miniature – one of the looming obstacles facing the current Israeli-Palestinian talks in the wake of this month's visit by President Bush. It is impossible to imagine any final peace deal which does not put Hebron – 12 miles east of the "green line" that marked Israel's eastern border until the Six Day War, and the site of some of the first Jewish settlements on Palestinian land which followed that victory – in the heart of a Palestinian state. When Marzel says "this is my house" it is an understated but forceful reminder that the Hebron settlers may prove the toughest to remove – as they would surely have to be if the occupation is ever to end – of any in the West Bank

Marzel is not alone in stalking Shaul. Enjoying the sport alongside him is Ofer Ohanna, the settlement security officer, who on a previous visit has goaded Shaul about a recent haircut. Noticing that the (heterosexual) Shaul had sheared off the pony tail which, along with his beard, black velvet kippa (or skullcap) and habitual sandals, has – ironically – long served to make him look like the more hippyish kind of settler, Ohanna had told him he had done it because "your boyfriend wouldn't go to bed with you if you didn't cut it off". Today, another prominent settler, Moshe Ben Batat, marches up to Shaul and demands more chillingly the date of his "mother's remembrance day" because "your mother threw you out of the house and committed suicide". (One – and only one – part of this is true. Shaul's mother did commit suicide, but during a post-natal depression – when Shaul was four years old.) Later still, the vociferous group of Shaul-stalkers is joined by David Wilder, the US-born spokesman of the Hebron settlers. Saying that Shaul's tours are "very dangerous", he adds that Shaul "feeds the enemy and plays into their hands" by criticising the settlers. Wilder sums up his view of Shaul: "Hamas with a kippa."

The man who attracts such hatred from the Hebron settlers has, at only 24, already led a remarkable life. He was described by the celebrated Peruvian writer Mario Vargas Llosa, to whom he acted as a guide in the city two years ago, as "one of the righteous this country has". He was a co-founder of Breaking the Silence, the growing group of dissident ex-soldiers – the core of whom served in Hebron at the peak of the intifada like him – who have testified on the persistent abuses they say the military has committed during the years of warfare.

Stationed in Bethlehem in the last few weeks of his military service he had "an enlightened moment" in which he says he began to understand what one of the group's later publications would call the "terrible moral price" exacted by the occupation from the young soldiers who serve in the West Bank and Gaza. Then and over the time that followed, Shaul began to find himself "in the very terrifying place [where] there is no justification for 90 per cent of the actions you took part in".

Since then he has become a political guide to, and activist in, the part of Hebron which was once its Arab commercial and cultural heart but which is now overwhelmingly dominated by the presence of 800 Jewish settlers. He has conducted or organised more than 200 tours of Israelis – including school and college students in their year before Army service – and foreigners. Last October, he and another ex-combat soldier, Avichai Sharon, briefed the international Middle East envoy Tony Blair on the daunting problems of inner-city Hebron.

To understand what led him to this unusual vocation, you have to climb with Shaul to look over the Palestinian city from a vantage point close to the old Jewish cemetery. As the afternoon muezzins ring out from the mosques, Shaul points out the red-roofed house where his unit's snipers and machine gunners were posted after giving the Palestinian family who lived in it half an hour to leave. At the peak of the intifada in 2002-03, with Palestinian gunmen using mainly assault rifles to shoot towards the settlements to their south at night, the Israeli soldiers were firing back grenades from machine guns.

"A grenade is not a bullet," Shaul explains. "It hits something and explodes, kills everyone in a radius of eight metres and injures everyone in a radius of 16. Secondly a machine gun is not an accurate weapon. You aim it a bit to the left and a bit to the right. If you're a real good operator you'll probably hit your target the fifth time."

Briefed initially by his platoon commander on the task, Shaul says he "freaked out. You still have a sense of a mission, of black and white, and I'm like, 'What's going on here? I'm supposed to shoot grenades into a city where people live?' The first night, you aim in the area of the target and you pull the trigger and you let it go as fast as you could and inside you're praying that the least amount of grenades were fired because if you pull the trigger for a minute around 60 grenades are out."

But as the week wore on, he says, it became "the exciting moment of the day. You're bored. You're stuck in this house. You don't go out. You play it like a video game with your joy-stick on top of the city – boom, boom, boom."

Shaul has no direct evidence of casualties from the salvos he fired – the "worst thing I did" – though he assumes there must have been injuries at the very least. It is something "you would prefer not to think about". And, yes, Palestinian snipers did indeed claim the lives of Jewish victims from the settlements – five since 2000. But Shaul says that the fire to which the military mainly responded in the way he describes habitually fell well short of the settlements.

The Israeli military employed draconian measures in Hebron during the peak of the intifada to protect the settlers – whose right to live in the city is not recognised in international law. These included imposition of curfews in the city centre (377 days in the first three years of the initifada), checkpoints (the UN counted more than 100 in the Israeli controlled sector of the city in 2005), comprehensive house-to- house searches in which Shaul says Palestinian families were sometimes locked into a single room while soldiers grabbed some sleep elsewhere in the house, and a refusal to intervene in many cases when settlers attacked or threw stones at local Palestinians.

According to a report earlier this year from the two most respected Israeli human-rights organisations, B'Tselem and the Association of Civil Rights in Israel (ACRI), "violence, arbitrary house searches, seizure of houses, harassment, detaining passers-by, and humiliating treatment have become part of daily reality for Palestinians and have led many of them to move to safer places". And while armed violence has significantly reduced inside the city, most of the restrictions on movement within the area of the settlements have remained. Shaul draws comparisons with other West Bank cities. "Does the IDF [Israeli Defence Force] have posts inside Nablus all the time? No. Inside Jericho? No. Inside Hebron? Yes. Why? Because you have the settlements here. H1 [the outer area of Hebron] is like all the rest of the Palestinian cities and H2 [the centre] is a ghost town; it's missing from the frame."

After a 13-year-old process of closures and segregation which began – ironically – with the Goldstein attack on Palestinians in the mosque, and continued through the intifada, there are now 304 closed shops and warehouses – 218 of them shut down by military order. The whole of the "sterile zone" protecting the settlements is closed to Palestinian vehicles. And the central section of Shuhada Street is closed to Palestinian pedestrians, except for four families who still live on this once densely populated but now desolate artery. The term used by B'Tselem and ACRI for the steady Palestinian depopulation of the area is "enforced eviction". Jan Kristiansen, a former head of the (already decade-old) Temporary International Presence in Hebron, described it as "ethnic cleansing".

An internal 2003 report produced by the Israel Defence Forces's civil administration cited a lengthy series of legal violations – mainly damage, break-ins and seizure of Palestinian property – by Hebron's Jewish settlers as they "consistently and systematically" worked to "establish and expand" their colony. "The leadership selects a target and broadcasts it a number of ways. Youths/teenagers burgle the building and even if they are driven away in the beginning, they eventually succeed. Youths/teenagers empty/burn the contents ... They enter through a common wall/the yard/narrow passageway between the properties without being noticed and begin to settle in." Adding that the activities of Jews in Hebron can be described as "if carried out under the protection of the Israeli regime", the report added: "The State of Israel looks very bad with regard to the rule of law in Hebron."

In December 2006, ACRI challenged the ban on pedestrians using much of Shuhada Street, pointing out that it had not been sanctioned by a written military order. The Army agreed it was indeed a mistake and issued a directive cancelling the prohibition. Some prominent local Palestinians were allowed to walk along the street after detention and body searches, and with a substantial military escort. Within a week the Palestinians were again told they were not allowed to use the route.

"We have a few hundred settlers there," says Shaul. "We don't even question it. They are Israeli citizens and they deserve protection, just like people in Tel Aviv. To give them the protection, we take a lot of things into consideration – we have geography, we have a budget, large numbers of soldiers – but there's one thing we won't take into consideration, and that's 166,000 Palestinians around here. This is the problem of Hebron. Only in this way can you close what used to be the main street for 60 years and then say it was a mistake and continue this mistake."

But, for Shaul, Hebron is also a paradigm of the wider West Bank, almost 40 per cent of which is now reserved for the settlers, along with the military apparatus and the roads – in many cases prohibited to Palestinians – that serve them. "If you zoom out of Hebron, if you look at the segregation, the methods, the tactics, Hebron is like the laboratory where things are tested before being used outside."

Another milestone in the long journey that led Shaul towards this point began early in his Army service. Shaul explains that the seminal historic event in every settler child's early education is the 1929 massacre during the riots against Jewish immigration to Palestine, when 67 Jews were slaughtered on a single day – though 435 survived after being sheltered by their Arab neighbours. And then he recalls how he saw an elderly Palestinian woman coming down from the hillside neighbourhood of Abu Snena to be greeted by settler children throwing stones at her. "I said to a child of about 10, 'What do you think you are doing?' He said, 'Do you know what this woman did in 1929?'"

We are now walking – a privilege exclusive to Israelis and foreigners – along Shuhada Street, past the abandoned stalls of the market area, illegally occupied by eight settler families from Avram Avinu after a Palestinian sniper killed a 10-month-old settler baby, Shalhevet Pass, in 2001. The settlers were finally issued with eviction orders in January 2006 – but then agreed to leave voluntarily after a remarkable deal with the Army under which they would be allowed to return after a few months. The deal was later overruled by Israel's Attorney General Menachem Mazuz.

As we pass to the left, leaving a manned Israeli checkpoint to the right, we come to the surreal lane where two Palestinian families still live amid a dozen settler families. We walk past the Abu Ayesha house, protected by wire mesh from the stones and garbage frequently thrown at it by the settlers. It was against this wire mesh that Jewish settler Yifat Alkobi pressed her face while repeatedly hissing "sharmuta" – whore – at her married Palestinian neighbour. The scene was caught in a video recording given to B'Tselem which shocked many Israeli viewers when it was shown on prime-time TV last January – including Tommy Lapid, the former Israeli Justice Minister who lost many of his family in the Holocaust. "In the years that preceded the Holocaust," he wrote, "behind shuttered windows hid terrified Jewish women, exactly like the Arab woman of the Abu-Ayesha family in Hebron." And where, according to testimony given by Taysir Abu Ayesha, Baruch Marzel broke into the house with 10 other settlers in the winter of 2002, beat him and attempted to drag him into the road before he was rescued by his stick-brandishing father.

And then we arrive at the end of the street and the home of Hani Abu Heikel, whose family was one of those who sheltered more than 400 of the Jews who survived the 1929 massacre. He says that the settlers from the neighbouring Al Bakri house have attacked his house with water pipes in the night, that his car has been attacked and burned four times and that in June most of the trees in the olive grove next to his house were ruined by being set on fire. When his son suggested to soldiers – some of whom, on this occasion, helped put the fire out – that they could identify the culprits by means of the ubiquitous cameras, he was told, says Mr Abu Heikel, that the cameras were for "security" – for the settlers' security, that is. The Abu Heikel family, a fixture of the Yehuda Shaul tours, are as pleased to see him as the settlers are displeased. "Yehuda, Yehuda," two-and-a-half-year-old Yara Abu Heikel shouts excitedly. The fact that Yehuda brings Israelis to the house has been, says Abu Heikel, especially valuable for his children. "I welcome it," he says. "I want them to know that the Israelis are not just the settlers. I wanted to show them that there are Jews who are not in conflict with us."

A tour round the inner city with a senior Israeli military official gives a very different take on Hebron from Shaul's. The official, who insists on anonymity, argues that while Palestinians are restricted in only three per cent of the city, Israelis are either barred or heavily restricted in the other 97 per cent. While ACRI and B'Tselem pointed out that a resident of the Old City wanting to cross one side of Shuhada Street to the other needs to go round the entire city centre and pass through a number of checkpoints, the Army insists that the restrictions on pedestrian movement in the city are "minimal". As for vehicles, the Army says that those carrying supplies like construction materials are allowed through with prior authorisation and that the required detours add only 10 minutes to the journey for Palestinians. The official stresses that the closures are needed for security reasons and insists, "I am responsible for the lives of Palestinians and Israelis. I am not just in charge of the Israelis."

This, of course, goes to the heart of the question of who bears the real burden of keeping the settlers safe. In the words of the ACRI/B'Tselem report, "Israeli law-enforcement authorities and security forces have made the entire Palestinian population pay the price for protecting Israeli settlement in the city." In doing so, it caused "the economic collapse of the centre of Hebron and drove many Palestinians out of the area." The Army repeatedly – and rightly – points out "that the rights of Israeli citizens to live in the city have been authorised by the decisions of the Israeli government." The military official says, moreover, that since the Goldstein massacre, which he adds was a "horrible thing" which brought "shame to the Jewish people all over the world", the principal "targets" of violence here have been not Palestinians but Israelis. "Since 1994 until today Israelis have been targeted by all the organisations of terror," he concludes.

Certainly, since the beginning of the intifada, Palestinian militants have killed 17 members of the security forces and five civilians – including 10-month-old Shalhevet Pass, shot by a Palestinian sniper in 2001. In Hebron as a whole, according to the ACRI/B'Tselem report, the security forces killed 88 Palestinians in the same period "at least 46 of whom (including nine minors) were not taking part in hostilities at the time they were killed". In addition two Palestinians were killed by settlers, one of them 14-year-old Nasseem Jamjoum, gunned down at her home by settlers in 2003 on the rampage after the shooting of a soldier/settler outside the city. No one was indicted for that shooting.

The official says that because "Hamas terror is strong" in the area, the soldiers consist of "the best units in the Israeli Army" – inevitably trained to defeat the militants rather than to keep the peace between civilian populations, But despite the human-rights groups' well-documented charge that soldiers repeatedly fail to intervene when an Israeli attacks a Palestinian or his property, the army insists that soldiers are under orders to do so. In general, the military official says, violent incidents between Palestinians and Israelis have fallen 50 per cent in 2006-07 from the level in 2003-04.

The official insists – rightly – that the decision about whether to allow settlements in Hebron is a matter for the politicians and not the military. But he is also clearly sympathetic to the argument that the Jews had a right after the Six Day War to reclaim property that had been historically Jewish. On the subject of the progressive takeover of Arab property since 1967, he repeatedly draws a distinction – not recognised in international law – between property that was historically Jewish and property that wasn't. He points, for example, to the Beit Hadassah settlement (which was taken over by settlers in 1979 though even Menachem Begin, the right-wing Likud Prime Minister at the time, was strongly opposed to the move). "This was a hospital that served all the neighbourhood, Jews and Muslims, until most of the staff were killed in the 1929 massacre," says the military official. "When Germany gave back property which had been taken from Jews, people in Israel were very proud," he says. "If we hadn't had the war in 1967 the emotion about recovering the property [in Hebron] would be the same."

For Yehuda Shaul, however, that argument – that there were always Jews in Hebron in the past – is no different from that of the "right of return" to Israel claimed by the families of Palestinian refugees who were forced to flee their homes in what is now Israel during the war of 1948, a claim consistently rejected by both Israel and the international community. And the argument that alternative routes, however tiresome, exist for Palestinians to the one through the old city centre of Hebron is as tenable as if "you said to people in West Jerusalem, you can no longer use Mahane Yehuda [the main Jewish market in the city] and Jaffa Street [the main artery of Jewish West Jerusalem]; you are going to have to go round it."

Nor is he impressed, as a religious Jew, by the argument that the settlers are needed to establish the right of Jews to pray at the Tomb of the Patriarchs. While even some Palestinians have suggested that in the event of a Palestinian State there could be guaranteed "safe passage" for those Jews who would want to pray at the Tomb, Shaul doubts that would be realistic, pointing out that no such permission existed before the occupation. Instead he suggests the price being paid is too high simply to "control the city of the patriarchs" and to allow access to the Tomb for the minority of religious Jews who use it now. "All this was done on the back of thousands of Palestinians who were more or less expelled from their lives," he says. "This is not Jewish. I'm an Israeli, I'm a Jew and I care what my society looks like, about what are the values that are at the heart of my country. And Hebron is a huge problem for my society and my country. There is a clear plan to cause the Arab population to leave the centre of Hebron."

Shaul doesn't for a moment deny the threat to settlers and soldiers. "You don't have to teach me about security problems," he tells today's visitors about his period serving in the city. "Hebron was a very dangerous place. Israelis were killed. But what we are doing on this tour is asking: what are the red lines we cannot cross?" David Wilder retorts: "His red line is that we shouldn't be here."

Many – possibly even a majority – of Israelis would indeed agree that the settlers should not be in Hebron. After the Goldstein massacre, Yitzhak Rabin wanted to expel them but was advised that it was politically impossible. Shaul does not use his tours to urge the withdrawal of the settlements from Hebron. Instead, "We just ask them: 'What do you think? You saw the price in human rights, in morality, in the lack of law, the price that Palestinians pay for 800 settlers in the heart of their city. And you saw the price the Israeli regime pays and Israeli society pays for running this place and you have to decide for yourself.'"