Rishi Sunak is one of many world leaders under pressure to reassess his government's support for Israel.
ADVERTISEMENTMore than 600 British jurists, including three retired judges from the UK Supreme Court, are calling on the government to suspend arms sales to Israel.
The move piles more pressure on Prime Minister Rishi Sunak after three UK aid workers were killed in an Israeli strike.
In an open letter to Sunak published late Wednesday, the lawyers and judges said the UK could be complicit in "grave breaches of international law" if it continues to ship weapons.
The signatories, among them former Supreme Court President Brenda Hale, said the UK is 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".
London is a staunch ally of Israel, but relations have been tested by the war's rapidly mounting civilian death toll.
While UK 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 (€49 million) in 2022 alone.
It provides components that make up 15% of the F-35 stealth combat aircraft, currently being used by Israel to relentlessly bomb Gaza.
Calls for an end to arms exports have escalated since an Israeli airstrike killed seven aid workers from the aid charity World Central Kitchen on Monday. Three of the dead were British nationals.
Israel claims 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 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."
Stop the supply
Britain is just one of a number of Israel's longstanding allies facing calls to cut off the supply of weapons and to push for a ceasefire in the conflict.
Peter Ricketts, a former UK national security advisor, said the 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.
In February, Canada announced it would stop future shipments.
That 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.
ADVERTISEMENTOther countries, including Israel's two biggest arms suppliers, the US and Germany, continue to allow weapons sales.