And he argued that a US-backed ceasefire was the best way to ensure their safety.

"We need to see humanitarian sites protected, and that's something that we continue to raise with Israel," Blinken told reporters on a visit to Poland.

Blinken, however, also placed some responsibility on Hamas, echoing Israeli accusations and talking points that lack solid evidence.

"We continue to see Hamas hiding in, taking over, and otherwise using these sites from which to conduct its operations," Blinken said.

The UN agency for Palestinian refugees UNRWA said six of its staffers had been killed in two Israeli air raids on the Nuseirat school and its surroundings, drawing statements of outrage around the world.

"I think it also underscores, once again, the urgency of reaching a ceasefire," Blinken said.

Blinken, who has been pushing for a truce deal for weeks, said a ceasefire was "the best way of ensuring that we have a genuinely protected space throughout Gaza."

He added that it would provide "a space in which the humanitarians can not only continue to do their work, but massively increase it to the benefit of people who desperately need it."

Israel's assault on Gaza has killed at least 41,118 Palestinians and wounded more than 95,125 others, according to the territory's health ministry. The UN rights office says most of the dead are women and children.

*This story was edited by Ahram Online.