The population of Gaza is starving to death due to constraints imposed on humanitarian aid, the World Health Organization's emergencies director Michael Ryan said on Wednesday.

The WHO said the risk of famine in the Palestinian territory was already high and on the rise, with the space for humanitarian intervention being increasingly squeezed.

"This is a population that is starving to death, this is a population that is being pushed to the brink," Ryan told a press conference.

"The civilians of Gaza are not parties to this conflict and they should be protected, as should be their health facilities.

"The Palestinian people in Gaza are right in the middle of a massive catastrophe," Ryan said, adding that things could get worse.

Ryan said access to proper nutrition had become a major issue in the Gaza Strip, with the calorie count and the quality of nutrition consumed by Gazans having dropped sharply.

Populations are not supposed to survive indefinitely on food aid, he said.

"It's supposed to be emergency food aid to tide people over.

"And if you mix a lack of nutrition with overcrowding and exposure to cold through lack of shelter... you can create conditions for massive epidemics," particularly in children.

"And we're seeing them," Ryan said.

The space for humanitarian intervention was being constrained in "every aspect", he added.

He pointed to the dramatic reduction in the number of operational health facilities and to how efforts to bring aid into the Gaza Strip were constantly disrupted and impeded.

An Israeli military excavator is pictured in the background at a position as displaced Palestinians flee from Khan Yunis in the southern Gaza Strip on January 30, 2024. Photo: AFP

'Extreme challenges'

The war was triggered by Hamas's October 7 attack on Israel, which resulted in the deaths of around 1,140 people, mostly civilians, according to an AFP tally based on official figures.

Militants also seized about 250 hostages. Israel says 132 of them remain in Gaza including at least 29 people believed to have been killed.

Following the deadliest attack in Israel's history, its military launched an air, land and sea offensive that has killed at least 26,900 people in Gaza, most of them women and children, according to the territory's health ministry.

WHO chief Tedros Adhanom Ghebreyesus said the agency was facing continued "extreme challenges" in propping up Gaza's health system.

"Over 100,000 Gazans are either dead, injured, or missing and presumed dead," he said.

"The risk of famine is high and increasing each day with persistent hostilities and restricted humanitarian access."

Tedros said the Nasser medical complex, the chief hospital in the southern Gaza Strip, was now operating with one ambulance, with patients being brought in on donkey carts.

The WHO attempted to deliver food to the hospital on Tuesday but that aid was stripped from the trucks "by crowds who are also desperate for food", said Tedros.