LONDON (AP) — More than 600 British jurists, including three retired judges from the U.K. Supreme Court, are calling on the government to suspend arms sales to Israel, piling pressure on Prime Minister Rishi Sunak after the deaths of three U.K. aid workers in an Israeli strike.

Britain is just one of a number of Israel's longstanding allies whose governments are under growing pressure to halt weapons exports because of the toll of the six-month-old war in Gaza.

THE KILLING OF AID WORKERS ADDS TO PRESSURE ON THE UK GOVERNMENT TO HALT ARMS SALES TO ISRAEL

In an open letter to Sunak published late Wednesday, the lawyers and judges said the U.K. could be complicit in "grave breaches of international law" if it continues to ship weapons.

Israel-Palestinians

People inspect the site where World Central Kitchen workers were killed in Deir al-Balah, Gaza Strip, Tuesday, April 2, 2024. World Central Kitchen, an aid group, says an Israeli strike that hit its workers in Gaza killed at least seven people, including several foreigners. (AP Photo/Abdel Kareem Hana)

Signatories, including former Supreme Court President Brenda Hale, said Britain 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."

Britain is a staunch ally of Israel, but relations have been tested by the mounting death toll, largely civilian, from the war. Calls for an end to arms exports have escalated since an Israeli airstrike killed seven aid workers from the aid charity World Central Kitchen, three of them British.

Israel says the attack on the aid workers was a mistake caused by "misidentification."

The U.K.’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."

British firms sell a relatively small amount of weapons and components to Israel. Defense Secretary Grant Shapps has said that military exports to Israel amounted to 42 million pounds ($53 million) in 2022.

Other allies of Israel are also facing calls to cut off the supply of weapons and to push for a cease-fire in the conflict, which has killed more than 32,000 Palestinians, according to health authorities in Gaza.

Spanish Prime Minister Pedro Sánchez said Thursday that his country had stopped selling weapons to Israel, and urged other nations to do the same. Sanchez said Wednesday that his government has 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.

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Germany is one of Israel’s closest allies in Europe and, given memories of the Holocaust, treads carefully when criticizing 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 U.K. national security advisor, said suspension of U.K. 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 U.S. as well, which would be the real game-changer," he told the BBC.