GENEVA, Sept 11, 2025 (BSS/AFP) - The UN's health agency said Wednesday its workers will remain in Gaza City despite calls from Israel's military for people to flee an assault it is mounting there.

"To civilians in Gaza: WHO and partners remain in Gaza City," the World Health Organization said on its X account.

Israel's army is intensifying its attacks on Gaza City -- the main urban centre in the besieged Gaza Strip -- with the goal of seizing the city. This week, it warned civilians there to leave.

The UN estimates that around one million Palestinians live in and around Gaza City.

"WHO is appalled by the latest evacuation order," the head of the UN agency, Tedros Adhanom Ghebreyesus, said on X.

He said the Israeli demand that the city's one million people go to what Israel was calling a "humanitarian zone" in the south of the Gaza Strip was unfeasible.

"The zone has neither the size nor scale of services to support those already there, let alone new arrivals," he said.

Tedros pointed out that half of the functioning hospitals left in the Gaza Strip were in Gaza City, and the territory's "crippled health system cannot afford to lose any of these remaining facilities".

He urged the international community to "act", saying that, in Gaza, "this catastrophe is human-made, and the responsibility rests with us all".

Israel has been waging offensive operations in Gaza since October 2023, following a deadly attack launched from there by Hamas that resulted in the deaths of 1,219 people, mostly civilians, according to an AFP tally based on Israeli figures.

Israel's retaliatory offensive has killed more than 64,000 Palestinians, most of them civilians, according to figures from the health ministry in Hamas-run Gaza that the United Nations considers reliable.

The UN has declared famine in parts of Gaza, which Israel contests.