Under "catastrophic" food insecurity, households suffer an extreme lack of food, leading to acute malnutrition in young children, an imminent risk of starvation, and deaths.
The World Food Programme has warned that a massive public health crisis is looming in Gaza due to the lack of clean water, food and medical supplies.
Gaza's environment was already suffering from recurring conflicts, rapid urban growth, and high population density, before the most recent conflict began on Oct. 7.
The offensive has left Gaza in ruins, killing more than 37,000 people, according to its health authorities, and left much of the population homeless and destitute.
Israel's treatment of Palestinian workers, under scrutiny for decades by the UN labour body, has increased since the October 7 war.
The UN agency has been unable to access its main warehouse in the south because it was in an evacuation zone, and the 2,700 tonnes of food inside were either looted or destroyed in the fighting.
It also cites a ruling by the International Court of Justice last week that ordered Israel to immediately halt its military assault on Rafah, in a landmark emergency ruling in South Africa's case accusing Israel of genocide.
Israeli attacks have devastated the Gaza Strip since the October 7 attack.
"There are reports of mass casualties, including children and women, among those killed. Gaza is hell on earth,” the UN organisation said.
The report, which was anticipated to address whether Israel's actions violated international law, fell short of conclusive judgment, prompting criticism from human rights advocates.
Egypt's Foreign Affairs ministry attributed the decision to the escalating severity and scope of Israeli attacks on Palestinian civilians in the Gaza Strip.
In its latest act of aggression against the people of Gaza, Israel seized that side of the Rafah border crossing with Egypt, forcing tens of thousands of Palestinians to flee.
Israel has shut down both the Rafah and Kerem Shalom crossings for aid and people as part of its military operation in Rafah.
This comes after Russia and China on Friday vetoed a US-led draft resolution that condemned a recent attack by Hamas but did not explicitly demand an immediate end to Israel's campaign in Gaza
UN Secretary-General António Guterres said Palestinians in Gaza are enduring horrifying levels of hunger and suffering.
UNRWA chief Philippe Lazzarini said he had "intended to go into Rafah today, but was informed my entry had been declined.
"The governments of the most powerful countries in the Western world have lost their dignity and any respect they might have had," she says.
The 10 non-permanent Security Council members expressed regret at the US veto, saying the 15-member organ must shoulder its responsibilities.
UN chief Antonio Guterres said that any assault on the city would "put the final nail in the coffin" of relief operations.
Heavy fighting again rocked Gaza on Wednesday as aid agencies warned of looming famine.