The United Nations on Friday insisted there was no safe place for Palestinians ordered to leave Gaza City and that Israel-designated zones in the south were "places of death".

Since launching its air assault on Gaza City in August ahead of its ground offensive there, the Israeli military has repeatedly told Palestinians to head south.

"The notion of a safe zone in the south is farcical," James Elder, a spokesman for the UN children's agency Unicef, said in Geneva.

Speaking from Deir al-Balah in central Gaza, Elder pointed to how "bombs are dropped from the sky with chilling predictability; schools, which had been designated as temporary shelters are regularly reduced to rubble, [and] tents... are regularly engulfed in fire from air attacks".

The Israeli military has urged Palestinians to relocate to a "humanitarian area" in Al-Mawasi on the coast, where it says aid, medical care and humanitarian infrastructure will be provided.

Israel first declared the area a safe zone early in the war but has carried out repeated strikes on it since, saying it is targeting Hamas.

Elder insisted that "the issuance of a general or a blanket evacuation order to civilians does not mean that those who remain behind lose their protection as civilians".

At the same time, he warned, the "so-called safe zones ... are also places of death".

Al-Mawasi, he pointed out, "is now one of the most densely populated places on Earth. It's grotesquely overcrowded and has been stripped of the most basic essentials of survival".

The UN had begun in late 2023 "debunking this concept of a unilaterally-declared safe zone", Elder said, stressing that "the law is very clear".

"It is the responsibility of the occupying power Israel to ensure that a safe zone has all the essentials for survival: that is nutrition, shelter and sanitation.

"None of those are present in a level that is fitting of a population," Elder said, adding that the UN at the start had "at least assumed that these places would not be bombed".

But over the past 18 months, the designated safe-zones had been hit "dozens of time", and "people in tents have suffered from airstrikes". (AFP)