A top Palestinian official and three other people were killed in a roadside bombing outside a restive refugee camp in southern Lebanon on Monday. Senior Palestine Liberation Organization (PLO) official Kamal Medhat, two of his bodyguards and another Palestinian official were traveling in a convoy when the bomb exploded at the entrance of the Mieh Mieh camp near the town of Sidon.

Medhat had visited the Mieh Mieh refugee camp to pay condolences to the family of Raef Naufal, the head of Fatah's Committee in the southern camp who died during armed clashes over the weekend.

"The bomb was apparently hidden in a little shed on the side of the road and was detonated as Medhat's convoy drove by," an army spokesman told AFP.

An army spokesman also told Elnashra news website Monday that the roadside bomb weighed between 30 and 50 kilograms.

Medhat, who was a close aide to the late Palestinian President Yasser Arafat, is the highest ranking Palestinian official killed in Lebanon since the PLO was forced to pull out of the country in 1982 after the Israeli invasion.

Medhat, 58, was the PLO's deputy representative in Lebanon and also a former intelligence chief for the mainstream Fatah movement in the country.

LBCI television quoted well-informed Fatah sources as saying that the bomb was meant to target the Palestinian Authority's representative in Lebanon, Abbas Zaki.

Zaki blamed Israel for the killing and warned it would have serious repercussions in Lebanon and the Palestinian camps.

"Those behind the killing are working in one way or another for Israel," said Zaki, who had left the camp in another vehicle just minutes before the blast. "We are trying to calm the situation inside the camps." Palestinian President Mahmoud Abbas, who is also the head of the PLO, "condemned this terrorist crime," according to a statement from his office.

In statement Monday, Hizbullah said the attack bore "the fingerprints of the Zionists and was aimed at sowing discord."

The bomb, made up of more than 20 kilograms of TNT, was detonated by remote control, Munir Maqdah, who is in charge of security at Lebanon's refugee camps, told AFP.

The other victims were identified as Akram Daher, who was in charge of the PLO's youth organization in Lebanon, and bodyguards Khaled Daher and Mohammed Shehadeh.

Maqdah said three people in a second car had been seriously wounded.

The force of the blast tore through Medhat's car and hurled it into a nearby olive grove.

Tensions have been running high in Mieh Mieh where two people died over the weekend in an apparent settling of accounts between rival clans.

Medhat "was on his way out of the camp where he had visited officials in a bid to ease the tension," Hisham al-Debsi, a PLO official, told AFP.

Medhat, also known as Kamal Naji, was a close aide to Arafat when the PLO chief was leading his guerrilla war against Israel from Lebanon.

The representative of the Palestinian Islamist faction Hamas in Lebanon, Osama Hamdan, condemned the killing, saying it was aimed at creating discord in Palestinian camps, considered breeding grounds for extremism.

Tension between Fatah and Islamist groups inside the camps has run high in the past year, with clashes and attacks leaving at least 12 dead.

The Lebanese Army does not enter the camps, leaving responsibility for security to Palestinian factions.

The explosive situation was brought to light in 2007 during fierce battles at the Nahr al-Bared camp in northern Lebanon between the army and Fatah al-Islam, an Al-Qaeda-inspired militia.

The fighting killed 400 people including 168 soldiers, and led to the army entering a Palestinian camp for the first time since the 1975-90 Civil War.

According to the UN agency for Palestinian refugees (UNRWA), there are between 350,000 and 400,000 refugees in Lebanon, most of them living in the 12 camps.

Other estimates put the number of refugees at 200,000 to 250,000 as UNRWA does not strike from its lists the names of those who emigrate.

Fatah's representative in Lebanon Sultan Abu al-Aynayn said the bomb that killed Medhat also aimed to "target Palestinian unity."

Abu al-Aynayn said that "it seems the fate of the Palestinians is sacrificing more blood."

"Accusations can be directed at many parties, but I am confident in the capability of the Lebanese Armed Forces to discover those responsible for committing this crime. I will not accuse a certain party or say whether the assassination was planned by parties involved in the internal Palestinian political struggle," he added, but did not rule out the possibility of Israeli involvement in the crime.

Education Minister Bahia Hariri condemned the blast and made a series of phone calls to top Palestinian officials to learn more on Medhat's killing.

Free Patriotic Movement leader MP Michel Aoun also condemned the assassination saying "the killing of moderates is always a bad sign."

The Amal Movement issued a statement condemning the blast, and said the bombing of Medhat's convoy "meant to jeopardize efforts for Palestinian reconciliation."

Amal also pointed the finger at Israel.

Amal urged Fatah and other Palestinian factions to cooperate with the Lebanese Army and security forces "in order to safeguard Lebanon's stability and security."

Echoing Amal, the Future Movement said the blast threatened Lebanon's security and urged the judiciary and security forces to uncover the perpetrators.