The food situation in the Gaza Strip is slipping deeper into catastrophe, with the risk of famine rising by the day, the UN's World Food Programme warned Tuesday.

A study conducted between November 24 and December 7 found that all 2.2 million people living in the Palestinian territory were in a crisis level of acute food insecurity, or worse.

The situation has only deteriorated since then, said Abeer Etefa, the WFP's senior Middle East spokeswoman.

"The situation in Gaza is of course slipping every day into a much more catastrophic situation," with "a looming threat of famine", she told a press briefing in Geneva, via video link from Cairo.

"The risks of having pockets of famine in Gaza is very much still there.

"More than half a million people in Gaza are facing catastrophic food insecurity levels and the risk of famine increases each day, as the conflict is limiting the delivery of life-saving food assistance to people in need."

The Gaza war broke out with Hamas's unprecedented October 7 attacks, which resulted in the deaths of about 1,140 people in Israel, mostly civilians, according to an AFP tally based on Israeli official figures.

In response, Israel has carried out a relentless offensive that has killed at least 25,490 people in Gaza, around 70 per cent of them women, children and adolescents, according to the health ministry in the Hamas-run territory.

Etefa said that around 70 per cent of requests to deliver food to northern Gaza were rejected by the Israeli authorities.

The last deliveries to the north were around January 11 and 13, carrying 200 tonnes of food for 15,000 people. 

"That's really very, very small numbers," the spokeswoman said.

"This is why we're seeing people becoming more desperate," as they have no confidence that the trucks will come again.

In January so far, over 730 trucks carrying more than 13,000 tonnes of food have crossed into Gaza, the WFP said.