The government is facing calls from opposition parties and senior Conservatives to publish the legal advice it has received on the war in Gaza following claims it has been warned Israel has breached humanitarian law.
Shadow foreign secretary David Lammy said Lord Cameron and Rishi Sunak should “come clean” on what they have been told.
It comes after a leaked recording of a senior Tory MP, who claimed ministers were concealing the advice.
Alicia Kearns, the chair of the Commons Foreign Affairs Committee, said she was convinced ministers had concluded Israel was not demonstrating a commitment to international law.
The Foreign Office has said it keeps advice on Israel’s compliance with international law under review but that it would remain confidential.
Israel has come under intense international scrutiny over its treatment of Palestinians since the start of the war against Hamas, which followed the October 7 atrocities in which 1,200 were killed.
In the leaked recording, of Ms Kearns answering questions at an evening drinks reception hosted by the West Hampstead and Fortune Green Conservatives in London on March 13, she said: “The Foreign Office has received official legal advice that Israel has broken international humanitarian law but the Government has not announced it.
“They have not said it, they haven’t stopped arms exports.
“They have done a few very small sanctions on Israeli settlers – and everyone internationally is agreed that settlers are illegal, that they shouldn’t be doing what they’re doing, and the ways in which they have continued and the money that’s been put in.”
Licences to export arms cannot be granted if there is a clear risk the weapons could be used in serious violation of international humanitarian law.
Ms Kearns told the Observer newspaper, which obtained the leaked recording: “I remain convinced the Government has completed its updated assessment on whether Israel is demonstrating a commitment to international humanitarian law, and that it has concluded that Israel is not demonstrating this commitment, which is the legal determination it has to make.
“Transparency at this point is paramount, not least to uphold the international rules-based order.”
A Foreign Office spokesman said: “We keep advice on Israel’s adherence to international humanitarian law under review and ministers act in accordance with that advice, for example when considering export licences.
“The content of the Government’s advice is confidential.”
Mr Lammy said Ms Kearn’s comments raise “serious questions about whether the Government is complying with its own law.
“David Cameron and Rishi Sunak must now (come) clean and publish the legal advice they have received.”
SNP Westminster leader Stephen Flynn accused the government of being “on the wrong side of history” on the issue.
He added that the PM and foreign secretary “owe it to the public and to the high offices they currently hold to be honest about whether they have received advice that Israel has breached international humanitarian law.
“If reports are to be believed, and the UK Government has continued to supply arms and intelligence to Israel whilst knowing they were in breach of international humanitarian law, then the position of both would be untenable.”
Lord Cameron has stressed Israel’s responsibilities under humanitarian law, including to ensure aid gets to civilians.