NEW YORK, May 5 (Reuters) - A top U.N. official on Sunday accused Israel of continuing to deny the United Nations humanitarian access in the Gaza Strip, where the U.N. food chief warned a "full-blown famine" has taken hold in the north of the enclave of 2.3 million people.

While not a formal famine declaration, World Food Programme Executive Director Cindy McCain said - in an NBC News interview broadcast on Sunday - that based on the "horror" on the ground: "There is famine, full-blown famine, in the north, and it's moving its way south."

Israel has continued to enhance its efforts to boost aid to Gaza, said COGAT, an Israeli Defense Ministry agency tasked with coordinating aid deliveries into Palestinian territories.

"In talks between Israeli and UN representatives, including @WFP, none of the entities indicated a risk of famine in northern Gaza," COGAT said in a post on X. "Noting the improved situation, int'l orgs stated last week that the volume of goods transported to northern Gaza must be reduced since the quantities are too high in relation to the population."

The head of the U.N. Palestinian refugee agency (UNRWA), Philippe Lazzarini, on Sunday accused Israel of continuing to deny the U.N. aid access in Gaza as it tries to avert famine.

"Only in the past 2 weeks, we have recorded 10 incidents involving shooting at convoys, arrests of UN staff including bullying, stripping them naked, threats with arms & long delays at checkpoints forcing convoys to move during the dark or abort," Lazzarini posted on X.

Lazzarini also called on "Hamas and other armed groups to stop any attacks on humanitarian crossings, refrain from aid diversion and make sure assistance reaches all those in need." The militants claimed responsibility on Sunday for an attack that shut down the main humanitarian aid crossing into Gaza.

A U.N.-backed report in March said famine was imminent and likely by May in northern Gaza, and could spread across the enclave by July. Famine is assessed as at least 20% of the population suffering extreme food shortages, with one in three children acutely malnourished and two people out of every 10,000 dying daily from starvation or from malnutrition and disease.

U.N. officials say that generally by the time a famine is formally declared somewhere it is too late to save many people. U.N. Secretary-General Antonio Guterres said last week that the most vulnerable in northern Gaza "are already dying of hunger and disease."

The U.N. has complained about a lack of humanitarian aid access throughout the seven-month-long war between Israel and Palestinian militants Hamas in Gaza. Guterres has said the U.N. is trying to avert "an entirely preventable, human-made famine" in northern Gaza.

Israel is retaliating against Hamas over an Oct. 7 attack in which Israel says the militants killed about 1,200 people and took more than 250 people hostage. Gaza health authorities say Israel has killed more than 34,600 people in Gaza since then.

Hamas came to power in Gaza in 2006 after Israeli soldiers and settlers withdrew in 2005, but the enclave is still deemed as Israeli-occupied territory by the United Nations.

As the occupying power, the U.N. human rights chief has said Israel is obligated to ensure the provision of food and medical care to the population and to facilitate the work of humanitarian organizations trying to deliver aid.

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