The UN's top rights and refugee officials have condemned Israel's bombardment of Gaza and warned of a major humanitarian crisis.
Navi Pillay, the UN human rights commissioner, on Thursday said that Israel had attacked homes, schools, hospitals, and UN premises in apparent violation of the Geneva Conventions.
Valerie Amos, the UN's humanitarian aid coordinator meanwhile told a UN Security Council meeting that there were now 440,000 displaced fleeing fighting in Gaza, and that hundreds of thousands more were without basic services, power and food.
And Philippe Krahenbuhl, the top UN refugee official in Gaza, said that the Palestinian territory was "facing a precipice" and said "the illegal blockade of Gaza must be lifted".
The comments came a day after Israeli shells hit a UN-run school which was being used as a shelter by more than 3,300 people. Nineteen people were killed, and many more wounded.
Pillay, who has previously condemned Israeli attacks on Gazan civilians, told a news briefing on Thursday: "The shelling of houses directly means a violation of Israel's obligation to protect the right to housing, right to food, right to clean water of Gazans, even as, under its obligation as an occupying force."
"Therefore I would say that they appear to be defying ... deliberate defiance of obligations that international law imposes on Israel."
She added that the Hamas group had also violated international humanitarian law by firing rockets into Israel.
Her statement was followed by Amos, who told a UN meeting that there was "no safe place in Gaza".
"We have all watched in horror the desperation of children, of civilians, as they have come under attack, with no safe place to go."
As of Friday, over 240,000 civilians are hosted in UN schools, while the rest are seeking refuge in hospital grounds, government buildings and homes of their families and friends, she said.
Amos also made an emergency appeal to the international community for more funds to help the displaced.
More than 1,400 Palestinians, mostly civilians, have died in the fighting, along with 56 Israelis, most of them soldiers.
Israel continued its bombardment on Thursday, with the prime minister, Benjamin Netanyahu, saying it would not end until the army had achieved its objectives.
Pillay also criticised the US, Israel's main ally, for failing to use its influence to halt the violence.
"They have not only provided the heavy weaponry which is now being used by Israel in Gaza, but they've also provided almost $1bn in providing the Iron Domes to protect Israelis from the rockets attacks," she said.
"No such protection has been provided to Gazans against the shelling."