A British aid worker who died on Friday in Jenin refugee camp was killed by Israeli gunfire, Israeli public radio has reported.

Iain Cook was shot by accident as he left his caravan with a mobile phone in his hand, according to an initial investigation by the Israel Defence Forces (IDF), the radio says.

A soldier thought it was an attempt to attack

Israel Radio quoting findings of initial investigation

"From the first results of the enquiry, it appears that the shots came from the Israeli side, and that a soldier fired in error at the employee," the investigation has found, Israel Radio said on Saturday.

The development comes after the United Nations expressed serious concerns about the killing and accused Israel of delaying an ambulance trying to reach the man.

UN Secretary General Kofi Annan said on Friday he was "deeply disturbed" by the death of Mr Hook, 53, who was working for the UN agency for Palestinian refugees (UNRWA) at the Jenin refugee camp.

He was involved in a project to rebuild homes which were destroyed during previous Israeli operations.

The circumstances of Mr Hook's death are still not clear.

Some reports speak of a gun battle as troops tried to seize an Islamic Jihad militant in the area.

Israel radio said Mr Hook was "hurrying out of the building, a mobile telephone in his hand, [and] a soldier thought it was an attempt to attack the soldiers".

Palestinians carry a symbolic stretcher with the UN flag

The UN says Mr Hook was trying to evacuate colleagues from the UN compound of caravans when he was shot.

The IDF would only say that the investigation is continuing. Officials had earlier rejected an assertion that the bullets found in Mr Hook's abdomen were of the type used by Israeli troops.

On Friday the UN accused Israeli soldiers of delaying an ambulance which had come to Mr Hook's aid.

The UN said in the statement he had died before reaching the hospital.

"It is not known at this time whether the delay resulted in the death," the statement said.

A Palestinian boy was also killed and an Irish woman was wounded in the Jenin refugee camp on Friday.

UK Foreign Secretary Jack Straw called Mr Hook's death a "terrible event" and expressed his condolences to his family and friends.

Mr Straw was telephoned by his Israeli counterpart, Benjamin Netanyahu, to express his regrets over the death, public radio also reported.

UNRWA's Commissioner-General, Peter Hansen, voiced "shock and outrage" at Mr Hook's death.

But he said he hoped Mr Hook's family would "take some small comfort and pride in the knowledge that he lost his life trying to save that of others."

Crackdown

The Israeli military, which regards Jenin as a hotbed of militants, surrounded the camp on Thursday night.

They also went into the town of Bethlehem in pursuit of militants after a suicide bombing in Jerusalem on Thursday which left 11 Israelis dead.

A 12-year-old boy throwing stones was killed by Israeli fire in Jenin, eyewitnesses and hospital officials said.

In a separate incident, Caoimhe Butterly, a young Irish woman active in a Palestinian solidarity group, told Irish radio she had been shot in the foot while trying to protect Palestinian children during the incursion.