GAZA CITY - UN chief Ban Ki-moon on Tuesday paid what he called a "heartbreaking" first visit to the war-battered Gaza Strip where Israeli troops remain deployed on the third day of a ceasefire.
Hours before the inauguration of US president-elect Barack Obama, the army said a total troop pullout from Gaza was not under discussion although the ceasefire was holding firm.
"For the moment, no one is talking about the total withdrawal of troops," said army spokeswoman Avital Liebovich.
Ban, describing the scenes in post-war Gaza as "heartbreaking," called for those responsible for the bombing of UN buildings to be held accountable following Israel's 22-day war on Hamas Islamists.
"It is an outrageous and totally unacceptable attack on the United Nations," Ban said, speaking outside the still-smouldering main UN compound in Gaza City.
"There must be a full investigation... there should be accountability through a proper judiciary system."
Ban became the first world leader to visit the enclave since Israel halted Sunday the deadliest offensive it has ever launched on the Palestinian territory, which has been ruled by Hamas since June 2007.
Four UN schools where Gazans were sheltering from the fighting were also hit by Israel. More than 40 people were killed in one such attack, according to medics and UN officials.
Israel has said it made very effort to prevent civilian deaths and said troops were fired upon from inside or near each of the UN sites in question.
Ban went on to accuse Israel of using "excessive force" in the conflict, but he also condemned Palestinian rocket fire on southern Israel as "completely unacceptable."
The UN chief was due to visit the southern Israeli town of Sderot, five kilometres (three miles) from the Gaza border, that has taken the brunt of the rocket fire since 2000.
Also calling for an investigation were eight Israeli human rights groups who accused the army of ignoring the rules of war.
They urged prosecutor general and government legal adviser Menachem Mazuz to act describing the scale of casualties among women and children as "terrifying."
Palestinian health ministry figures list more than 1,300 people dead, including 410 children and about 100 women. Another 5,300 were wounded -- 1,855 of them children and 795 women.
"The rules of war seem to have been held in total contempt forcing Israel to open an independent inquiry immediately," the groups said.
Meanwhile, Israeli soldiers shot dead a Palestinian farmer in the north of the strip, doctors said.
An Israeli army spokesman said she could not confirm the report that the man had been killed near the town of Jabaliya by shots fired by troops close to Gaza's border with Israel.
And two Palestinian children died in Gaza City when an Israeli shell they had been playing with exploded, doctors said.
Israel launched its massive assault on December 27 and started to pull out gradually from the territory on Sunday as Hamas and other militant groups pledged a week-long ceasefire.
Gazans say the tide of global hope that has surged with Obama's election victory has not washed over their homeland.
"Obama won't bring my husband back to life," said Leila Khalil. "He was martyred and left me with six children to feed on my own. And Obama won't repair our house that was damaged in the (air) raids."
For Khalil, Obama, who was to be inaugurated as the 44th president of the United States later Tuesday, will not alter the historically pro-Israel US policy on the Middle East.
"No one cares about us," she said. "If we can't even count on Arab presidents, what can we hope for from an American president when they've always supported Israel?"
The Palestinian bureau of statistics reported 4,100 homes totally destroyed and 17,000 others damaged in the offensive.
In Kuwait, an Arab summit ended with aid pledges to help rebuild Gaza, but without a specific fund or political unity on the war.
Emir Sheikh Sabah al-Ahmad al-Sabah called for "practical steps to stabilise the ceasefire," and Saudi King Abdullah pledged one billion dollars for reconstruction.
The rebuilding of Gaza looks set to become another battleground with Israeli Prime Minister Ehud Olmert warning Israel did not want Hamas to take control of reconstruction.
"Israel believes that the reconstruction process must be led by international organisations in cooperation with the UN, Egypt and the Palestinian Authority," he said.