Britain is not just complicit in Israel’s breaches of humanitarian law in Gaza but a participant that has repeatedly ignored its legal obligation to prevent a genocide, witnesses have told the independent Gaza tribunal.

The two-day tribunal in London, which is independent of government and parliament, is seeking to amass evidence of Britain’s failure to distance itself from what the tribunal organisers regard as Israeli war crimes amounting to genocide.

It is chaired by Jeremy Corbyn, who claimed the 29 witnesses had “paved the way for truth” and promised he would demand a meeting with the foreign secretary to present the report he will now compile with two legal experts.

The second and final day of evidence, given mainly by experts supportive of Palestine, painted a picture of a government that has done the minimum to hold Israel to account and the maximum to shield itself from parliamentary and judicial scrutiny. The concern for government is that the evidence becomes a widely believed charge sheet against ministers as Israel resists all compromise in its fight against Hamas.

Among the allegations made were that:

No 10 failed to provide the support requested by lawyers acting for James Henderson, the British World Central Kitchen aid worker killed by the IDF on 1 April 2024, leaving them reliant on an IDF internal investigation, with a coroners’ inquiry still as long as two years away.

Britain provided no support to the chief prosecutor at the international criminal court, Karim Khan, after the US government imposed sanctions that led a British bank to close his account, “so emboldening those who seek to dismantle international accountability”.

Forz Khan, a lawyer acting for the family of Henderson, said: “The Henderson family want to know what the full picture is. He went out there in good faith, yet he was for some unknown reason murdered, picked off in a military fashion. An internal IDF investigation found that it was a mistake. Our case is that it was a deliberate murder.”

Khan also claimed that when the Henderson family were finally given a meeting with ministers, their lawyers were prevented from attending.

Henderson was killed when an Israeli airstrike targeted a clearly marked vehicle. The Israeli inquiry led to the dismissal of two officers. An inquiry by the IDF found a drone operator mistakenly targeted the convoy after thinking it had been taken over by Hamas gunmen.

Some of the most damaging evidence was given by Charlotte Andrews-Briscoe, a lawyer acting for the Palestinian human rights group Al-Haq in the UK court challenge into the handling of arms exports controls to Israel.

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She said evidence revealed in the case that the UK Foreign Office passed all allegations of war crimes to Israel “setting in motion a circular reasoning, which saw the government repeatedly give perpetrators of these atrocities the opportunity not to incriminate themselves”.

By September 2024, the last time Al-Haq lawyers had disclosure in court, 40,000 Palestinians had been killed and 10,000 airstrikes launched. However, the UK government had examined 413 cases, and lawyers had found the only possible violation of international law involving World Central Kitchen.

“That meant, 11 months into this deadly war, the UK government had not found a single incident that exclusively killed Palestinians and had been a possible violation of international law.”

The Israeli government says it does not target children or civilians, but says its task is made harder by Hamas, which carried out the 7 October 2023 attacks and still holds Israeli hostages, embedding itself among the civilian population.

Mark Smith, a diplomat who quit his Foreign Office job over the UK’s refusal to stop selling arms to Israel in August 2024, said civil servants who challenged the IDF’s methods were routinely pressed to tone down their findings “so it sounded less bad”.

“Thousands of conversations within the walls of the Foreign Office on the most controversial aspects of our arms sales policy will never be seen by the public [and] never be put to a court because they were held in person,” he said.