(Reuters) - Prime Minister Benjamin Netanyahu said on Tuesday Israel mistakenly killed seven people working for the aid charity World Central Kitchen in a Gaza airstrike, and the U.S. 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, which was founded by celebrity chef Jose Andres, said its staff were traveling in two armored cars emblazoned with the charity's logo and another vehicle, and had coordinated their movements with the Israeli military.

"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 pledged an investigation by "an independent, professional and expert body".

At least 196 humanitarian workers have been killed in Gaza since October, according to the United Nations, and Hamas has previously accused Israel of targeting aid distribution sites.

In a call on Tuesday, British Prime Minister Rishi Sunak told Netanyahu that Britain was appalled by the deaths, which included three Britons, and demanded a thorough and transparent independent investigation, Sunak's office said.

Australian Prime Minister Anthony Albanese said he expressed "anger and concern" to Netanyahu in a separate call.

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.

U.S. President Joe Biden called WCK founder Andres to express condolences. Washington will press Israel to do more to protect aid workers, the White House said.

"These people are heroes, they run into the fire, not away from it," U.S. 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."

The United Nations, which has warned of a looming famine in Gaza, again called for an immediate humanitarian ceasefire, spokesperson Stephane Dujarric said.

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.

The aid convoy was hit as it was leaving its Deir al-Balah warehouse after unloading more than 100 tons of food aid brought to Gaza by sea, WCK said.

"This is not only an attack against WCK, this is an attack on humanitarian organizations showing up in the most dire of situations where food is being used as a weapon of war," said Erin Gore, chief executive of World Central Kitchen.

"This is unforgivable."

The U.S.-based charity said it would pause its work in Gaza, and the United Arab Emirates, which has financed the seaborne food deliveries to Gaza that WCK distributed, said it was putting the shipments on hold pending safety guarantees from Israel and a full investigation.

Anera, a U.S.-based aid group that works in part with WCK, said on Tuesday it too was pausing operations in Gaza because of safety concerns.

INCREASING ISRAELI ISOLATION

Australia, Britain and Poland, countries which have generally been friendly towards Israel, all demanded action to protect aid workers, underscoring Netanyahu's increasing diplomatic isolation over Gaza.

Israel has been under rising international pressure to alleviate severe hunger in Gaza, which has been shattered by Israel's offensive against the Palestinian Islamist group Hamas. The conflict began after Hamas attacks on southern Israel on Oct. 7 that killed 1,200 people, according to Israeli figures.

Since then, much of the densely populated territory has been laid waste and most of its 2.3 million population displaced. More than 32,000 Palestinians have been killed, according to the health ministry in Hamas-ruled Gaza.

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 Feb. 29, in which around 100 people were killed as they awaited an aid delivery.

Hamas, Gaza's dominant group, has said the main problem with aid distribution is Israeli targeting of aid workers. After the latest incident, it issued a statement saying the attack aimed to terrorize workers of international humanitarian agencies, deterring them from their missions.

Andres, who started WCK in 2010 by sending cooks and food to Haiti after an earthquake, said he was heartbroken and grieving for the families and friends of those who died in the airstrike.

"The Israeli government ... needs to stop restricting humanitarian aid, stop killing civilians and aid workers, and stop using food as a weapon," he said.

Video obtained by Reuters showed a large hole in the roof of a four-wheel-drive WCK vehicle and its burned and torn interior, as well as paramedics moving bodies into a hospital and displaying the passports of three of those killed.

Conditions in Gaza remain extremely precarious with fighting going on in several areas on Tuesday and 71 people killed in Israeli strikes over the past 24 hours, according to Gaza health authorities.