"Israel's evacuation orders appear designed to cut off North Gaza completely from the rest of the territory," Turk told a press conference at UN headquarters in New York.

"As bombing and other attacks continue, there are serious concerns about a large-scale forcible transfer of civilians not meeting the requirements of international law for evacuation on imperative military grounds," he said.

"Forcible transfer of a large part of the population of North Gaza would amount to a war crime."

Israel is pursuing its offensive against Gaza, in the wake of the October 7, 2023 attack.

Israel's campaign in Gaza has killed 42,438 people, the majority women and children, according to data from the health ministry in the Hamas-run territory, which the UN considers reliable.

The Israeli army has intensified its operations over the past 10 days or so in northern Gaza, where hundreds of thousands of people are trapped in the fighting, and where it has become difficult to deliver humanitarian aid.

"I call on Israel immediately to facilitate the massive influx of humanitarian aid that is needed across all parts of Gaza," Turk said.

The captives
 

Israel's President Isaac Herzog on Thursday called for swift action to bring back captives held in Gaza, as he hailed the killing of Hamas leader Yahya Sinwar by Israeli forces.

Herzog on social media platform X said the slain Hamas chief "has for years been responsible for heinous acts of terrorism against Israeli civilians", also calling on Israeli leaders to "act in every way possible to bring back" the remaining captives.

Israeli Foreign Minister Israel Katz said that the killing of Hamas leader Sinwar provided an "opportunity" to release captives held in Gaza and to remove the Hamas group from the Palestinian territory.

"The elimination of Sinwar creates an opportunity for the immediate release of the hostages and paves the way for a change that will lead to a new reality in Gaza, one that is without Hamas and Iranian control," Katz said in a statement.

The Israeli military on Thursday announced the killing of Hamas leader Sinwar by its forces in southern Gaza the previous day.

The Israeli military "confirms that after a year-long pursuit, yesterday (Wednesday), October 16, 2024, IDF (military) soldiers from the Southern Command eliminated Yahya Sinwar, the leader of the Hamas terrorist organisation, in an operation in the southern Gaza Strip," it said in a statement.