"We are pausing the delivery of aid through Kerem Shalom, the main crossing point for humanitarian aid into Gaza. The road out of this crossing has not been safe for months. On 16 November, a large convoy of aid trucks was stolen by armed gangs," UNRWA head Philippe Lazzarini said in a post on X.

"Yesterday, we tried to bring in a few food trucks on the same route. They were all taken," he added, warning hunger was "rapidly deepening" in Gaza.

Lazzarini listed how the humanitarian operation had become "unnecessarily impossible" due to "the ongoing siege, hurdles from Israeli authorities, political decisions to restrict the amounts of aid, lack of safety on aid routes and targeting of local police".

He called on Israel to ensure aid flowed to Gaza and said the country "must refrain from attacks on humanitarian workers".

This follows an Israeli strike on Saturday that killed three contractors of the US charity World Central Kitchen.

The United Nations said last month that 333 aid workers had been killed since the start of the war in October of last year, 243 of them employees of UNRWA.

Lazzarini reiterated his call for a ceasefire "that would also secure the delivery of safe and uninterrupted aid to people in need".

Israel, which imposed a total siege on the Palestinian territory, denies blocking aid despite mounting evidence less trucks have entered Gaza compared to pre-war levels.

Anti-poverty charity Oxfam in March said in a report that Israel was continuing to "systematically and deliberately block and undermine any meaningful international humanitarian response" in the Palestinian territory.

Jens Laerke, spokesman for the UN humanitarian agency OCHA, said in February that it has become nearly impossible to evacuate the sick or wounded and deliver aid in northern Gaza, with the situation increasingly difficult in the south.

He added that Israeli forces have "systematically" blocked access to people in besieged areas, complicating the delivery of aid.

Israel's war on Gaza has so far killed 44,382 Palestinians and wounded more than 105,142, according to figures from the territory's health ministry which the United Nations considers reliable.

The war has destroyed vast areas of the coastal enclave and displaced 90 percent of the population of 2.3 million, often multiple times. Hundreds of thousands have crammed into squalid tent camps, where conditions have worsened as the cold, wet winter sets in.

*This story was edited by Ahram Online.