Every single person in war-torn Gaza is expected to face high levels of acute food insecurity in the next six weeks, a report by the UN's hunger monitoring system said on Thursday.

The five-scale food insecurity classification, known as the IPC, forecast in its "most likely scenario" that by February 7 "the entire population in the Gaza Strip (about 2.2 million people)" would be at "crisis or worse" levels of hunger.

"This is the highest share of people facing high levels of acute food insecurity that the IPC initiative has ever classified for any given area or country," it said.

International alarm has mounted over the plight of Gazans enduring daily bombardment, food and water shortages and mass displacement.

The Integrated Food Security Phase Classification (IPC) rates hunger levels from one to five.

The report warned that some 50 percent of the population are forecast to be in the "emergency" phase – which includes very high acute malnutrition and excess mortality – by February 7.

And "at least one in four households," over half a million people, would be facing "Phase 5" catastrophic conditions, it predicted.

"Even though the levels of acute malnutrition and non-trauma related mortality might not have yet crossed famine thresholds, these are typically the outcomes of prolonged and extreme food consumption gaps," it said.

International humanitarian organisation Care said the figures were "alarming."

The war in Gaza began when its Islamist rulers Hamas infiltrated Israel on October 7 and killed around 1,140 people, mostly civilians, and abducted 250, according to a tally based on Israeli figures.

Israel responded with a relentless air and ground campaign. The Hamas government's media office in the Gaza Strip said on Wednesday at least 20,000 people have been killed, among them 8,000 children and 6,200 women. (AFP)