The UN's World Health Organization (WHO) and World Food Programme (WFP) said they had been able to increase deliveries of supplies into the Gaza Strip after the fragile ceasefire took effect on January 19 following more than 15 months of war.

Meanwhile UNRWA, the chief aid agency for Palestinians, told a media briefing in Geneva it was committed to continuing its work despite Israel severing ties on Thursday.

- WHO demands medical evacuations -

Speaking from Gaza, Rik Peeperkorn, the WHO's representative in the Palestinian territories, said health needs in the densely populated strip were "immense", amid the "large-scale devastation of the health system".

Only 18 out of 36 hospitals in the besieged territory are even partially functional. Just 57 of the 142 primary health care centres are operational, along with 11 field hospitals.

Before the ceasefire, many attempts to deliver critical aid to Gaza were impeded due to strict restrictions imposed by the Israeli authorities, according to UNRWA and NGOs.

The flow of health aid has now begun to rise, Peeperkorn said. WHO has received 62 delivery trucks and 22 more were expected over the next two days.

He said hospitals at least now had fuel to operate.

The WHO wants to expand hospital bed capacity and hopes to get a pre-fabricated hospital up within four to five weeks in the north.

Peeperkorn said bed capacity was 3,500-4,000 before the war and is currently around 1,500-1,900. The WHO wants to increase it to 2,000-2,500 as soon as possible.

Gaza had a pre-war population of around 2.4 million people. About 90 percent have been displaced, some repeatedly, since it began in October 2023.

Peeperkorn said the mental health burden in Gaza was "unimaginable".

The WHO estimates that 12,000 to 14,000 people, including 2,500 children, need medical evacuation from Gaza for urgent treatment.

"Medical evacuations must urgently resume and a medical corridor must open now," he said.

WHO is expecting on Saturday the first medical evacuation since the ceasefire, and the first via the Rafah crossing into Egypt since it was closed on May 6 last year.

Around 50 patients are due to leave.

Only 480 patients have been medevaced since May 6.

"If we continue at this pace we have, we will be busy for the next 15 years," said Peeperkorn.

- WFP boosting bakeries -

The WFP said that since the ceasefire began, around 600 trucks of humanitarian aid had been entering Gaza daily, including 50 carrying fuel.

Between January 19 and Tuesday, WFP has delivered more than 10,300 metric tonnes of food -- more than double the amount delivered in the whole of December and triple that in October.

WFP said there were enough pre-positioned supplies -- waiting at borders for Israeli clearance to enter Gaza -- to feed more than a million people for three months.

The agency has been providing high-energy biscuits to displaced people returning north.

Antoine Renard, WFP's country director for the Palestinian territories, said the agency wants to restore bakeries to provide affordable bread.

He said prices for key staples had started to drop within Gaza, although they remained very high.

Some prices are now between 100- and 1,000-percent higher than before the war, down from 2,000-3,000 percent higher prior to the ceasefire.

- UNRWA continuing work -

UNRWA has vowed to continue working in the Palestinian territories, despite Israel cutting ties with the agency on Thursday.

Israel has accused UNRWA of providing cover for Hamas militants -- something the UN and many donor governments dispute.

Spokeswoman Juliette Touma said UNRWA remained the backbone of international aid to Gaza and a halt to its services would have "catastrophic consequences".

"If UNRWA is not allowed to continue to bring and distribute supplies, then the fate of this very fragile ceasefire is going to be at risk," she warned.

Palestinian colleagues in the Gaza Strip and the West Bank were facing an "exceptionally hostile environment as a fierce disinformation campaign against UNRWA continues", she added.

As for the agency's funding, Touma said: "Our financial situation is very unclear."

"The last thing that we want is to suspend our services because of lack of funding," he added.

Hamas's attack in Israel on October 7, 2023, resulted in the death of 1,205 people on the Israeli side, most of them civilians, according to an AFP tally based on official Israeli figures, which includes hostages killed in captivity.

More than 47,460 Palestinians, a majority of them civilians, have been killed in Israel's military offensive on Gaza since October 2023, according to data provided by the health ministry in Hamas-run Gaza.

The UN has acknowledged these figures as reliable.