United Nations workers issued a petition yesterday demanding the Israeli army stop the "harassment, beating and killing" of UN staff.

The petition comes less than two weeks after Iain Hook, a British UN worker, was shot dead by an Israeli soldier inside a UN compound as he tried to evacuate his staff.

"For two years, United Nations staff have been subject to escalating harassment and violence by Israel's military, so that the protection supposed to be afforded by the blue letters of the UN is being steadily eroded," said the petition, which was signed by 64 UN staff working in Israel and the occupied territories.

An Israeli military source said: "We reject the suggestion Israeli soldiers intentionally try to harass UN personnel. We respect their work, and that includes our commitment to their safety".

But the petition reflects growing fear among UN staff, and anger at the Israeli army's attempts to explain away Mr Hook's death. The UN has dismissed as "not credible" claims by the Israeli army that Palestinian gunmen were inside the UN compound when Mr Hook was shot.

The petition follows a UN demand for an explanation from the Israeli army over the destruction of food worth $270,000 (£172,000) that was to be distributed to Palestinians.

Soldiers blew up a warehouse containing more than 500 tons of food that belonged to the UN's World Food Programme (WFP) in the northern Gaza Strip at the weekend.

In a recent report, the American government aid organisation USAid found that 20 per cent of Palestinian children under the age of five suffer from malnutrition. The report warned of a looming "humanitarian disaster".

In a statement that showed signs of official patience wearing thin, Kofi Annan, the UN secretary general, said he "once again" called on the Israeli authorities "to live up to their commitments and obligations to facilitate emergency humanitarian assistance in the occupied Palestinian territory".

The warehouse was destroyed during a raid on the Gaza Strip town of Beit Lahiya on Saturday night. It appears the Israeli army destroyed the building because they believed a wanted militant was hiding inside. There were apartments on the upper floors.

"The landlord told the soldiers food from the UN was being stored on the ground floor," said Jean-Luc Siblot, the country director for WFP in Jerusalem.

"There was a WFP sticker on the door. There was a UN flag on the building. They entered it and searched before destroying the building. They knew. That's the fact I find a little bit difficult to swallow."