A belief that every Palestinian child is a potential terrorist may be leading to a "spiral of injustice" and breaches of international law in Israel's treatment of child detainees in military custody, a delegation of eminent British lawyers has concluded in an independent report backed by the Foreign Office.

The nine-strong delegation, led by the former high court judge Sir Stephen Sedley and including the UK's former attorney-general Lady Scotland, found that "undisputed facts" pointed to at least six violations of the UN convention on the rights of the child, to which Israel is a signatory. It was also in breach of the fourth Geneva convention in transferring child detainees from the West Bank to Israeli prisons, the delegation said.

Its report, Children in Military Custody, released on Tuesday, was based on a visit to Israel and the West Bank last September funded and facilitated by the Foreign Office and the British consulate in Jerusalem.

It makes 40 specific recommendations concerning the treatment of Palestinian child detainees.

The issue has come under increasing scrutiny by human rights organisations and visiting delegations over the past year. In January the Guardian highlighted the use of solitary confinement in a report on the experiences of children under the military justice system.

The lawyers' report says Israel has international obligations as the occupying power in the West Bank, and its system of military law must respect human rights and non-discrimination. It points out that under international law, no state is entitled to discriminate in the exercise of justice on the basis of race or nationality. It says, however, that "there are major differentials between the law governing the treatment of Palestinian children and the law governing treatment of Israeli children".

The report compares the military justice system in the West Bank to the Israeli civilian legal system, finding key differences in the treatment of children. The most egregious are the length of time child detainees can be held a) before being brought before a judge (up to 24 hours for Israeli children compared with eight days for Palestinian children); b) without access to a lawyer (48 hours compared with 90 days); and c) without charge (40 days compared with 188 days). The minimum age for custodial sentences is 14 for Israeli children, but 12 for Palestinian children.

As well as meeting government officials, lawyers, NGOs and UN agencies, the British team also interviewed former child prisoners and former Israeli soldiers, and visited the military court at Ofer prison near Jerusalem, which holds regular child sessions. They witnessed children being brought into the court in shackles.

The report also details "two irreconcilable accounts of the treatment and rights of Palestinian children" given to the delegation. One was from Palestinian and Israeli NGOs, UN agencies, lawyers, former Israeli soldiers and former child detainees; the second from Israeli government officials, military judges and prosecutors.

The first included night-time arrests, the use of blindfolds and painful plastic wrist ties, physical and/or verbal abuse, the failure to be informed of the right to silence or to see a lawyer, solitary confinement, self-incrimination, children being made to sign statements in Hebrew which they could not understand and extremely restricted access to family. "In this process, every year hundreds of Palestinian children are traumatised, sometimes irreversibly, are denied part of the their schooling and then live at ongoing risk of much harsher punishment if they are arrested again," the report said.

In the second account it heard, children are informed of their rights, treated appropriately, subject to procedural safeguards, and violence and threats are forbidden. "In custody, children receive education to such a high standard that Palestinian children have been known to offend in order to access it," the delegation was told.

Among the report's recommendations are:

• An end to night-time arrests, except in extreme and unusual circumstances.

• Children should be told of their rights in their own language.

• Children should never be blindfolded or hooded.

• Single plastic hand ties should never be used.

• The prohibition on violent, threatening or coercive conduct towards children should be strictly observed.

• Children should not be shackled at any time.

• Any confession in a language other than the child's own should not be accepted as evidence.

• Solitary confinement should never be used "as a standard mode of detention or imprisonment".

• All Palestinian children should be held in facilities in the occupied territories, and not transferred to Israel, a breach of article 76 of the fourth Geneva convention.

In conclusion, the report says: "It may be that much of the reluctance to treat Palestinian children in conformity with international norms stems from a belief, which was advanced to us by a military prosecutor, that every Palestinian child is a 'potential terrorist'. Such a stance seems to us to be the starting point of a spiral of injustice."

Marianna Hildyard QC, one of the delegation, told the Guardian: "Israel claims to be a state committed to the rule of law and international standards. To make good that claim, it must formulate a legal structure for all Palestinian children in compliance with the convention of the rights of the child and international law. Further steps must be taken to close the gaps between the treatment of Israeli and Palestinian children."

In a statement, the Israeli embassy in London said it appreciated the delegation's efforts "to learn about the challenges involved in dealing with minors involved in acts of militancy and violence. Regrettably, such activities continue to be encouraged by official Palestinian textbooks and television programmes which glorify terrorism and suicide terrorists. As a result under-18 year olds are frequently involved in lethal acts … with the Palestinian Authority unable or unwilling to meet its obligation to investigate and prosecute these offences, Israel has no choice but to do so itself."

Israel would study the report's recommendations "as part of its ongoing efforts to find the most appropriate balance between preventing violence and treating perpetrators with humanity".

Rough justice

Hamza K, 15, arrested 5 January 2011

"At around 2.30am, I was sleeping … when I woke up to soldiers screaming through loudspeakers and saying: 'Open up immediately'. I looked out of the window and saw many military jeeps and soldiers with their lights focussed on the house … When the soldiers saw me, they pointed their weapons at me."

Malek S, 16, arrested 9 January 2011

"One of [the soldiers] tied my hands behind my back with one set of plastic cords and tightened them. He also blindfolded me. They took me out and forced me to stand near a military truck near the house … One of them hit me so hard in the testicles and I felt much pain."

Husam S, 15, arrested 12 September 2011

"The two interrogators kept me standing and never allowed me to sit in a chair. They kept slapping me around, but I never confessed. The interrogation lasted about two hours. After that, they printed out some papers in Hebrew and forced me to sign them. Later on it turned out that I had signed a confession saying I threw stones. This is what my lawyer told me later in court."

Rami J, 17, arrested 24 October 2011

"I was detained in Cell No 36 [in Al Jalame prison in Israel]. It is a very small cell, which had a mattress on the floor and a toilet with a horrible smell, as well as two concrete chairs. The lights in the ceiling were dim yellow and on 24 hours a day, and they hurt my eyes. The walls were grey and had a rough surface. The cell had no windows, just two gaps for letting air in and out. The food was served through a flap in the door … I eventually decided to confess because of the pressure they put on me. I was in a bad psychological state." (Rami J was held in solitary confinement for 24 days)

Malek Z, 15, arrested 4 July 2011

"'You better confess,' [the interrogator] shouted, but I never confessed. He was typing what I was saying in the computer. Then he printed it out in Hebrew and ordered me to sign it, but I refused so he slapped me hard across the face while shouting. He got up and pushed me towards the wall and I slammed against it. I was so scared of him I immediately signed the papers."