UN Secretary-General urged Israel this evening to show restraint after an army attack on a Gaza refugee camp that killed 10 people including two employees of a UN humanitarian agency, a spokesman said.
Mr Annan was "gravely concerned" by the predawn attack on the Bureij refugee camp by Israeli troops backed by tanks and helicopter gunships, UN chief spokesman Mr Fred Eckhard said, noting the assault fell during Eid al-Fitr, one of Islam's most important holidays.
"The secretary-general deplores the loss of innocent civilian life. He has repeatedly urged Israel to refrain from the excessive and disproportionate use of deadly force in civilian areas," Mr Eckhard said.
"He wishes to remind the government of Israel of its obligations as an occupying power to protect the civilian population, and urges them to ensure that the Israeli Defense Forces behave with greater restraint and discipline and in conformity with international humanitarian law," Mr Eckhard said.
The Israeli army said its troops met fierce resistance in the three-hour incursion, which it said was intended to root out militants responsible for attacks on troops in Gaza in a more than two-year-old Palestinian uprising for independence.
The UN Relief and Works Agency, in a statement issued in Gaza City, identified two employees as among the dead, bringing to five the number of UNRWA staff killed this year.
Mr Osama Hassan Tahrawi (31) an attendant at UNRWA's Bureij Boys' Preparatory School, was killed along with six friends and relatives by a rocket fired from a helicopter as he stood in his yard watching the military operation, UNRWA said.
Ms Ahlam Riziq Kandil, a 32-year-old school teacher at UNRWA's Bureij Elementary Co-educational School, was hit while in her home and died of her injuries after being taken to hospital, the relief agency said.
Among the UNRWA dead this year was Briton Mr Iain Hook, killed by Israeli soldiers last month in a clash in the West Bank city of Jenin.
Israel said its troops probably mistook Mr Hook for a gunman, but an outraged Mr Annan wrote to Israeli Prime Minister Ariel Sharon last week urging his government to identify and punish the soldiers responsible for Mr Hook's death.
UNRWA Commissioner-General Peter Hansen pledged an in-depth investigation of the deaths and branded as "completely unacceptable" the heavy civilian toll from today's attack.
"I must condemn what appears to be the indiscriminate use of heavy firepower in a densely populated civilian area," UNRWA quoted Mr Hansen as saying.
The Palestinians killed in Bureij refugee camp raid were buried this afternoon as crowds of angry men around the cemetery vowed to avenge their deaths.
"We are committed to the continuation of jihad and martyr operations until our land is liberated," members of the hardline group Hamas shouted through loudspeakers. "We will defeat the forces of the pigs!", said some Hamas militants. Martyrs operations is the term used by Palestinian groups for suicide attacks.
Israeli troops backed by tanks and helicopters raided the refugee camp in a pre-dawn move. Palestinian witnesses said Israeli soldiers, along with 25 tanks and several helicopters entered the camp.
Palestinian gunmen returned fire and a helicopter fired a missile into a street, killing at least three people.
One tank shell narrowly missed a Palestinian home, wounding five people, medics said. A second home, belonging to a Palestinian militant, was blown up by Israeli forces, witnesses said.
A doctor at the local hospital said nine Palestinians died and six were wounded - including the woman who later died - in the violence. The Israeli army said most of those killed were gunmen.
The high death toll and the timing of the assault, during the Muslim Eid el-Fitr holiday marking the end of the holy month of Ramadan, enraged Palestinians and tens of thousands attended a funeral for the 10 victims.
The raid also came just a day after Israeli Prime Minister Ariel Sharon said Osama bin Laden's al-Qaeda network was in Palestinian-ruled areas of the Gaza Strip and in Lebanon. Palestinians and Lebanon denied Mr Sharon's charge.