Prime Minister Benjamin Netanyahu says an Israeli airstrike had mistakenly killed seven people working for the aid charity World Central Kitchen in Gaza, and the US, Australia and other allies called for explanations amid widespread condemnation.
Israel's military voiced "sincere sorrow" over the incident, which ratcheted up international pressure for steps to ease the disastrous humanitarian situation in Gaza nearly six months into Israel's siege and invasion of the Palestinian enclave.
The strike on the World Central Kitchen convoy killed citizens of Australia, Britain and Poland as well as Palestinians and a dual citizen of the United States and Canada.
WCK said they were travelling in two armoured cars emblazoned with the charity's logo and another vehicle.
"Unfortunately in the past day there was a tragic event in which our forces unintentionally harmed non-combatants in the Gaza Strip," Netanyahu said in a video statement.
"This happens in war. We are conducting a thorough inquiry and are in contact with the governments. We will do everything to prevent a recurrence."
The Israeli military (IDF) pledged an investigation by "an independent, professional and expert body".
Britain summoned Israel's ambassador in London to express its "unequivocal condemnation of the appalling killing" of the WCK workers, three of whom were British nationals, and called for an urgent explanation from Israel of how this had occurred.
The United States, Israel's closest ally, said that there was no evidence Israel deliberately targeted the aid workers but that it was outraged by their deaths and Israel had an obligation to ensure aid workers in Gaza were not harmed.
The White House said it expected a broad and impartial investigation to be carried out with appropriate accountability.
"These people are heroes, they run into the fire, not away from it," US Secretary of State Antony Blinken said of the seven aid workers, speaking to reporters in Paris. "We shouldn't have a situation where people who are simply trying to help their fellow human beings are themselves at grave risk."
Israel has long denied accusations that it is hindering the distribution of urgently needed food aid in Gaza, which it has besieged in a war since October, saying the problem is caused by international aid groups' inability to get it to those in need.
Despite co-ordinating movements with the Israeli military, the convoy was hit as it was leaving its Deir al-Balah warehouse after unloading more than 100 tonnes of humanitarian food aid brought to Gaza by sea, WCK said.
"This is not only an attack against WCK, this is an attack on humanitarian organisations showing up in the most dire of situations where food is being used as a weapon of war," Erin Gore, chief executive of World Central Kitchen, said.
"This is unforgivable."
The United Arab Emirates, which had been the main financier for WCK's aid efforts through the maritime corridor, said it was pausing such shipments from Cyprus pending further safety guarantees from Israel and a full investigation.
Australia, Britain and Poland, countries which have generally been friendly towards Israel, all demanded action to protect aid workers, underlining Netanyahu's increasing diplomatic isolation over the situation in Gaza.
At least 196 humanitarian workers have been killed in Gaza since a Hamas attack on Israel on October 7 triggered Israel's assault on the Hamas-ruled enclave, and the deaths of the WCK staffers were "the inevitable result of the way this war is currently being conducted", UN spokesperson Stephane Dujarric said.
Israel has been under rising international pressure to alleviate the severe hunger in Gaza, which has been devastated by months of fighting the Palestinian Islamist group Hamas.
Much of the densely populated territory has been laid waste and most of its 2.3 million population displaced.
The United Nations and other international groups have accused Israel of hindering aid distribution with bureaucratic obstacles and failing to ensure the security of food convoys, underlined by a disaster on February 29, in which about 100 people were killed as they awaited an aid delivery.
