GENEVA, Switzerland - The World Health Organization on Thursday slammed the lack of safety guarantees for bringing humanitarian aid into the Gaza Strip, saying it was near impossible to get medical supplies to hospitals.

The WHO said the health needs in the Palestinian enclave were soaring while its ability to address them was plunging.

The UN health agency has been able to deliver 54 metric tonnes of humanitarian supplies into the territory over the past fortnight but said that would not even begin to address the scale of need.

"WHO will do everything we can to ensure that all people in Gaza have access to life-saving health and humanitarian services," WHO chief Tedros Adhanom Ghebreyesus told a press conference.

"In the current situation this is almost impossible."

The WHO's emergencies director Michael Ryan said the basic safety of staff on the ground in Gaza could not be guaranteed at the moment -- something he branded "unconscionable".

He said the organisation had never found it as difficult to establish basic rules of engagement regarding minimum safety guarantees for humanitarians.

- Hospital resupply obstacles -

"It is the responsibility of all parties to the conflict to allow those hospitals to be resupplied," Ryan said.

"Occupying authorities have a special responsibility to ensure that such facilities are not only protected, but serviced and supplied with the adequate needs for the populations that they serve.

"Right now, we have no deconfliction effectively operating. There is no humanitarian access.

"It has been almost impossible to set up appropriate notification acknowledgement and deconfliction measures."

Getting medical supplies to where they are needed "has not been facilitated, that has not been supported; in fact, if anything, quite the opposite".

Israel has heavily bombarded Gaza since Hamas gunmen stormed across the border on October 7, killing 1,400 people, mostly civilians, and kidnapping at least 240 others, including children, according to Israeli officials.

The Hamas-run Gaza health ministry says more than 9,000 people have been killed since the war with Israel erupted, mostly women and children.

- 'Horror' -

"We are running out of words to describe the horror unfolding in Gaza," Tedros said.

"The situation on the ground is indescribable. Hospital crammed with the injured, lying in corridors; morgues overflowing; doctors performing surgery without anaesthesia.

"And everywhere, fear, death, destruction, loss.

"As health needs soar, our ability to meet those needs is plummeting.

"It is too late to help the dead now. But we can help the living."

Israel describes Gaza's biggest hospital Al-Shifa as a de facto Hamas "command centre" and headquarters.

"We know what's going on above the ground... we have no information on what may be happening elsewhere or underneath these facilities," said Ryan.

Tedros added that there could be "no justification for Hamas’s horrific attacks on Israel", and reiterated his call on Hamas to release the hostages.

"And we call on all who can to de-escalate this conflict, rather than inflame it," he added.