Officials in the Department for Business and Trade (DBT) have raised concerns with senior civil servants that they may be liable if it is deemed Israel has broken international law.

       The Public and Commercial Services Union (PCS), which represents civil servants, has requested an urgent meeting with the department to discuss “the legal jeopardy faced by civil servants who are continuing to work on this policy”.

       The letter, sent on Wednesday, said: “Given the implications for our members we believe there are ample grounds to immediately suspend all such work.

       “We therefore request that you meet with us urgently to discuss this matter and cease work immediately.”

       The correspondence shows the PCS has been asking the government for its legal advice on arming Israel since January, when a preliminary ruling from the International Court of Justice (ICJ) found Israel’s acts in Gaza could amount to genocide, reports the i newspaper.

       A response to the union dated March 13 said “the question of criminal liability for civil servants is very unlikely to arise”.

       Britain is a staunch ally of Israel, but relations have been tested by the mounting death toll, largely civilian, from the war.

       Lord Dannatt, the former head of the British Army, said Mr Sunak would “do well to take note of” a letter signed by more than 600 lawyers which called on the Government to suspend sales.

       He said there are both moral and legal issues about the supply of arms to Israel and the UK “needs to stay on the right side of both of those lines”.

       He told Sky News: “I think the Prime Minister will do well to take note of, I am told it is as many as 600 senior judges and lawyers, who have signed this letter. And I think their experience and their interpretation of the law, international law, needs to be taken very seriously.

       “And I think the British government needs to do, as the Prime Minister has said, scrutinise very carefully what it is doing in terms of supplying equipment to Israel to make sure that we are staying on the right side of the law.

       “And of course it is not just a legal issue, there is a major moral issue here too which the atrocious attack 36 hours ago which killed seven aid workers really underlines.

       “There are moral issues and there are legal issues and I think the UK being the sort of country that it is, needs to stay on the right side of both of those lines.”