In a quiet voice, a woman speaking in Hebrew reads the names and ages of just a few of the more than 190 Palestinian children killed in Gaza in the last two weeks of intensive Israeli air strikes.

Describing the ad’s content as “politically controversial”, the Israeli Broadcasting Authority banned the 1 minute, 25-second spot produced by local human rights group B’Tselem.

But although the Palestinian child victims of this latest round of Israeli air strikes and Hamas rocket barrages will go unnamed in Israel's mainstream media, their toll grows by the day.

At least 800 Palestinians have been killed, at least 605 of them civilians and 190 of them children, while 5250 have been injured, the Ministry of Health in Gaza said.

Aid agencies said a Palestinian child had been killed every hour over the last two days.

That toll may rise again following an attack on a United Nations school in Gaza sheltering Palestinians displaced by the ongoing fighting. At least killed 15 people were killed – many of them children – and more than 200 were wounded, as gruesome images of panic, death and fear emerged from the Beit Hanoun Elementary Co-Ed A and D school compound in the north of Gaza Strip.

“The scenes of carnage and human suffering that we witnessed today at our elementary school in Beit Hanoun were so appalling and intolerable, that it is difficult to find the words to convey adequately my indignation,” said the UNRWA Commissioner General Pierre Krahenbuhl. “As has happened so many times in this pitiless conflict, civilians are paying the highest price of the current military escalation.”

Hundreds of Palestinians had taken shelter at the school after being displaced from their homes by the fighting, he said.

As the security situation around Beit Hanoun rapidly deteriorated, the UN attempted to negotiate with the Israeli Defence Forces for a pause in its operations in order to guarantee a safe corridor to relocate staff and displaced people.

“Approval for that never came,” Mr Krahenbulh said. “In addition, the school’s coordinates had been formally conveyed to the Israeli authorities on 12 occasions, most recently at 10:56 this morning.”

The IDF disputes the UN’s account of events, insisting in a statement released last night that there was a four-hour window period in which the UN could have evacuated the school.

“Hamas prevented the civilians from leaving it and once again used their infrastructure and international symbols as human shields,” the IDF said, appearing to cast doubt on whose rockets – Israel’s or Hamas’s – landed in the UN school.

“Several rockets launched by Hamas from within the Gaza Strip landed in the Beit Hanoun area,” it said. “During the intense fighting in the area, militants opened fire at IDF soldiers from the school area. In order to eliminate the threat posed to their lives, they responded with fire toward the origins of the shooting. The IDF is still reviewing the incident.”

Israel military fatalities stand at 32 since the operation commenced, while 134 soldiers were wounded in the fighting, and one soldier is believed to be missing, Israeli media reported.

It was the fourth time in as many days a UN school had been hit by explosions, the UN said.

Earlier in the week UNRWA revealed it had discovered, for a second time, a cache of rockets hidden in one of its vacant schools in Gaza. The school is situated between two other UNRWA schools providing shelter for around 1500 internally displaced people. UNRWA issued a similar statement after employees found 20 rockets in a different Gaza education facility on June 16.

At least 117,468 Palestinians are sheltering in 77 schools across the Gaza Strip as the renewed conflict enters its 18th day.

The attack on the school comes a day after the United Nations Human Rights Council has voted to establish a war crimes inquiry into the Gaza conflict, with suggestions that both Israel and Hamas had likely committed war crimes with indiscriminate attacks on civilians.

The council condemned Israel’s assault on Gaza, which it said involved "disproportionate and indiscriminate attacks".

While United States Secretary of State John Kerry was in Egypt pushing for a cease-fire, Israel’s Prime Minister Benjamin Netanyahu remained defiant over Israel’s actions.

He told a cabinet meeting: “We are continuing Operation Protective Edge at full strength, in the air and on the ground.”

And later, in a joint press conference with new British Foreign Secretary Philip Hammond, Mr Netanyahu said: “The terrorists are firing rockets from schools, from mosques, from hospitals, from heavily civilian populations and we have to try and are doing our best to minimise civilian casualties. But we cannot give our attackers immunity or impunity.”

But in an oped published on Friday in the left-leaning Haaretz newspaper, Sabri Saidam, an adviser to Palestinian President Mahmoud Abbas, wrote: “There is no military solution to this conflict, and there can be no peace with occupation and oppression.”

“The end of occupation is the only path towards lasting peace and security. By providing Israel with the conditions for total impunity, the international community has contributed in the consolidation of the extremist camp in Israel and its presence in power and has drifted us away from peace.”

Meanwhile aid agencies are warning that 1.2 million people, or two-thirds of Gaza’s 1.8 million population who are trapped in the 42-kilometre strip, have had their water and sewage services either cut completely or severely disrupted as a result of Israeli air strikes on key water infrastructure.