A U.N. official called on Israel to offer more protection for aid workers, as hunger experts warned that Gaza was at high risk of famine.

United Nations aid agencies have been demanding that the Israeli authorities do more to protect aid workers in the Gaza Strip and ensure that assistance reaches those who need it, Stéphane Dujarric, a U.N. spokesman, said on Tuesday.

The agencies are struggling to deliver food and other basic necessities. A report from the Integrated Food Security Phase Classification, or I.P.C., a partnership of U.N. bodies and relief agencies, concluded on Tuesday that Gaza was at high risk of famine. It also found that almost 500,000 people there, almost a quarter of the population, faced starvation.

On Monday, a high-ranking U.N. security official contacted the Israeli agency overseeing aid to Gaza to press for more protections for aid workers, Mr. Dujarric said, adding that a letter this month to the agency from the U.N.’s humanitarian coordinator had made similar points.

Israeli authorities have resisted blame. On social media on Tuesday, in a post directed at the U.N.’s World Food Program, the Israeli agency overseeing aid in Gaza displayed a photo of supplies that it said were waiting at an offloading area. “Stop making excuses and start playing your role as a humanitarian food organization and the head of the logistic cluster,” it said.

Monday’s I.P.C. report found that the amount of food reaching northern Gaza had increased in recent months, but it underscored the dire conditions people in the enclave were facing and the need for much more aid to be delivered.

Aid groups say they fear for the safety of their workers. The U.N.’s World Food Program suspended deliveries of assistance from the U.S.-built pier off the coast of Gaza this month after it said that its warehouses had been struck in an Israeli hostage rescue mission that killed scores of Palestinians, including women and children.

Last week the U.N. said that Gaza had become the most dangerous place in the world for aid workers. About 250 aid workers have been killed since the Hamas-led attack on Oct. 7 set off this war, the U.N. said. That figure includes nearly 200 who worked for UNRWA, the main U.N. agency for Palestinians.

That temporary suspension of deliveries from the pier has left aid sitting ever since and prompted concerns that the U.N. might halt other operations.

Mr. Dujarric noted the dangers to aid workers and said that humanitarian operations had repeatedly been targeted, pointing to Israeli strikes on hospitals and other areas that were supposed to be “de-conflicted.” The Israeli military said those locations were being used by Hamas militants.

“The risks, frankly, are becoming increasingly intolerable,” Mr. Dujarric said. He added that the need to support millions of Palestinian civilians dependent on humanitarian aid to survive was a priority and that the U.N. assessed the security situation daily to try to operate safely.

Juliette Touma, a spokeswoman for UNRWA, said that the humanitarian operation in Gaza had become “totally unnecessarily one of the most cumbersome and complex in the world right now.”