Nationals from Poland and Australia were also killed, as well as a Palestinian who was driving the car they were all travelling in. The nationality of the fifth person remains unknown.

Ismail al Thawabta, a spokesperson for the Gaza government's media office, said Israel was responsible for their deaths.

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The volunteers were employed by the World Central Kitchen, which provides food for displaced Palestinians.

In a statement, the charity said: "This is a tragedy. Humanitarian aid workers and civilians should NEVER be a target. EVER."

Founder José Andres described the volunteers as "angels" who had served around the world - and said he was grieving for their families.

He added: "The Israeli government needs to stop this indiscriminate killing. It needs to stop restricting humanitarian aid, stop killing civilians and aid workers, and stop using food as a weapon.

"No more innocent lives lost. Peace starts with our shared humanity. It needs to start now."

Israel Defence Forces said it is "conducting a thorough review at the highest levels to understand the circumstances of this tragic incident".

In a statement, a spokesperson added: "The IDF makes extensive efforts to enable the safe delivery of humanitarian aid."

Australia's Prime Minister Anthony Albanese offered his condolences to the family and friends of the Australian aid worker who died in the incident, who he named as Zomi Frankcom.

Mr Albanese said he has contacted the Israeli ambassador to ask for accountability over Ms Frankcom's death.

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Footage showed the bodies of those killed at al Aqsa Martyrs hospital in the central Gaza town of Deir al Balah. Several of them wore protective clothing marked with the charity's logo.

The workers' car was hit by an airstrike just after crossing from northern Gaza - and it is believed they were helping to deliver aid that had arrived hours earlier on a ship from Cyprus.

Founded by celebrity chef Jose Andres in 2010, the World Central Kitchen said last month it had served more than 42 million meals in Gaza over 175 days.

Mr Andres described those who died as "several of our sisters and brothers" - and wrote on X: "These are people... angels... I served alongside in Ukraine, Gaza, Turkey, Morocco, Bahamas, Indonesia.

"They are not faceless... they are not nameless."

The aid ships that arrived on Monday carried some 400 tons of food and supplies in a shipment organised by the United Arab Emirates and the World Central Kitchen.