US President Joe Biden has condemned Israel's killing of seven humanitarian aid workers in Gaza.

Saying he was "outraged and heartbroken", he accused Israel of not doing enough to protect aid workers.

Israel promised an independent investigation after the UK, US, Canada, Australia and Poland lost nationals in Monday's attack.

Israeli President Isaac Herzog has apologised for the deaths.

Mr Biden called for Israel's investigation to be conducted swiftly, and said it "must bring accountability" and its findings be made public.

Distributing aid in Gaza had been "so difficult", he said, because Israel had "not done enough to protect aid workers trying to deliver desperately needed help to civilians".

In some of his strongest language since the war began, Mr Biden also accused Israel of not doing enough to protect Palestinian civilians.

"The United States has repeatedly urged Israel to deconflict their military operations against Hamas with humanitarian operations, in order to avoid civilian casualties," the US leader said.

Humanitarian aid to Gaza is in doubt after WCK - a key provider of aid to the Strip - suspended operations.

Three of the killed aid workers were British nationals. A Polish national, an Australian, a Palestinian and a dual US-Canadian citizen were also killed. The Israel Defense Forces (IDF) has promised an independent investigation into the incident.

UK Prime Minister Rishi Sunak spoke to Israeli Prime Minister Benjamin Netanyahu on Tuesday. On the call, he described the situation in Gaza as "increasingly intolerable" and "demanded a thorough and transparent independent investigation" into the killing of the aid workers.

Mr Sunak added that Israel needed to end restrictions on humanitarian aid and protect civilians, according to a Downing Street statement.

Acknowledging that Israel's forces had hit "innocent people", Mr Netanyahu pledged an independent investigation.

"Unfortunately, in the last 24 hours there was a tragic case of our forces unintentionally hitting innocent people in the Gaza Strip," he said.

"It happens in war, we check it to the end, we are in contact with the governments, and we will do everything so that this thing does not happen again."

WCK - founded by celebrity chef José Andrés - is one of the main suppliers of aid to Gaza. Four days ago, it said that it had served 42 million meals in the territory - dispatching more than 1,700 food trucks and also sending close to 435,000 meals by sea.

The charity has said it will pause its operations in the region immediately. "We will be making decisions about the future of our work soon," it said in a statement.

According to Cogat, the Israeli defence ministry body in charge of civilian policy in the Occupied Palestinian Territories, WCK is responsible for 60% of the non-governmental aid getting into the territory.

A second charity, the American Near East Refugee Aid (Anera), which was working closely with WCK, told the BBC it was also freezing its operations in Gaza.

Mr Sobol, Mr Abu Taha and Mr Flickinger worked on WCK's relief team, which Ms Frankcom led, while Mr Chapman, Mr Henderson and Mr Kirby were part of its security team.

All seven were "heroes", the chief executive of WCK said.

"We have countless memories of them giving their best selves to the world. We are reeling from our loss. The world's loss," Erin Gore said in a statement.

According to the charity, the aid convoy was hit while leaving the Deir al-Balah warehouse, "where the team had unloaded more than 100 tons of humanitarian food aid brought to Gaza on the maritime route".

The convoy was made up of three vehicles, including two that were armoured, which clearly displayed the charity's logo. All three were hit during the strike.

WCK said it had co-ordinated the convoy's movements with the IDF.

More than 196 aid workers have been killed in Gaza since October, according to the US-funded Aid Worker Security Database, which records major incidents of violence against aid personnel. Not all have been killed in the line of duty.

Much of the Gaza Strip has been devastated during the Israeli military operations that began after Hamas gunmen attacked southern Israel on 7 October, killing about 1,200 people and seizing 253 hostages.

About 130 of the hostages remain in captivity, at least 34 of whom are presumed dead.

More than 32,916 people have been killed in Gaza since then, the Hamas-run health ministry says.