Britain is only one of several long-standing Israel allies whose governments are under growing pressure to halt weapons exports because of the toll of the six-month-old war in Gaza.
In an open letter to Sunak published on Wednesday, the lawyers and judges said the UK could be complicit in “grave breaches of international law” if it continues to ship weapons.
Signatories, including former Supreme Court President Brenda Hale, said Britain was legally obliged to heed the International Court of Justice’s conclusion that there is a “plausible risk of genocide” in Gaza.
The letter said the “sale of weapons and weapons systems to Israel … falls significantly short of your government’s obligations under international law”.
Israel says the attack on the aid workers was a mistake caused by “misidentification”.
The UK’s main opposition parties have all said the Conservative government should halt weapons sales to Israel if the country has broken international law in Gaza.
Several senior Conservatives have urged the same, including Alicia Kearns, who heads the House of Commons foreign affairs committee.
Sunak has not committed to an arms export ban, but said on Wednesday that “while of course we defend Israel’s right to defend itself and its people against attacks from Hamas, they have to do that in accordance with international humanitarian law”.
British firms sell a relatively small amount of weapons and components to Israel. Defence Secretary Grant Shapps has said military exports to Israel amounted to £42 million in 2022.
Other allies of Israel are also facing calls to cut off the supply of weapons and to push for a ceasefire in the conflict, which has killed more than 32,000 Palestinians, according to health authorities in Gaza.
Spanish Prime Minister Pedro Sanchez said on Thursday his country had stopped selling weapons to Israel, and urged other nations to do the same. Sanchez said his government had left “the door open” to diplomatic actions against Israel over its “insufficient” explanation of the aid workers’ deaths.
In February, Canada announced it would stop future shipments, and the same month a Dutch court ordered the Netherlands to stop the export of F-35 fighter jet parts to Israel. The Dutch government said it would appeal.
Other countries, including Israel’s two biggest arms suppliers, the United States and Germany, continue to allow weapons sales.
Germany is one of Israel’s closest allies in Europe and, given memories of the Holocaust, treads carefully when criticising Israel. But Chancellor Olaf Scholz has increasingly voiced unease, asking Netanyahu at a meeting last month how any goal can “justify such terribly high costs”.
Peter Ricketts, a former UK national security adviser, said suspension of UK arms sales would not change the course of the war, but “would be a powerful political message”.
“And it might just stimulate debate in the US as well, which would be the real game-changer,” he told the BBC.