U.N. says that without fuel it can no longer distribute humanitarian aid.

The United Nations said on Monday that its already dwindling reserve of fuel in the Gaza Strip would run out as soon as Tuesday, preventing the organization from receiving and distributing the desperately needed aid trickling in, and imperiling the only lifeline for the 2.2 million people in the coastal enclave.

The U.N.’s agency for aiding Palestinians, UNRWA, has been the main coordinator of humanitarian aid crossing into Gaza from Egypt since Israel placed Gaza under siege. Trucks carrying essential goods such as water, food, medicine and hygienic products go to U.N. warehouses in Gaza, where they are unloaded and distributed in other trucks by the U.N. and humanitarian agency partners, the U.N. said.

Andrea De Domenico, the head of the U.N. Office for the Coordination of Humanitarian Affairs for Palestinian territories, told reporters on Monday that as of Tuesday the U.N. will no longer have enough fuel to operate either the fork lifts that unload the goods or the trucks that distribute them.

As part of its offensive against Hamas, Israel has cut off electricity to Gaza and blocked the delivery of fuel, saying Hamas uses it for rocket attacks and has stockpiled fuel intended for civilians. More than one million Gazans have been displaced, and civilians are running perilously low on basic human necessities.

“Instead of a much-needed increase of this assistance, we have been informed by colleagues of UNRWA that, due to the lack of fuel, as of tomorrow the operations of receiving trucks will no longer be possible,” Mr. De Domenico said from Jerusalem.

A total of 980 trucks carrying essential aid have crossed into Gaza from Egypt, including 76 trucks on Sunday, Mr. De Domenico said. But the U.N. has said far more is needed. Before Hamas attacked Israel on Oct. 7, about 500 trucks of humanitarian aid crossed into Gaza daily.

The U.N. is worried that the fuel shortage could impede its humanitarian operations and the ability of hospitals, which rely on generators in the absence of power, to treat patients. Gaza’s main hospital, Al-Shifa, has reported that the lack of fuel was putting patients in intensive care at risk of dying and that premature babies were taken out of incubators that were now useless. Three babies and two cardiology patients had died as of Monday, according to Al-Shifa officials.

Al-Shifa’s critical infrastructure — including its water tanks, oxygen stations, maternity ward and cardiovascular facilities — was damaged by the fighting, Mr. De Domenico said. Three nurses were killed, he said.

Operational conditions for U.N. staff and humanitarian workers in Gaza were deteriorating by the hour, Mr. De Domenico said. Even if fuel were delivered outside, it would be too dangerous for hospital staff members to retrieve it, he said, because of snipers in the area.

“Lives in Gaza are hanging by a thread due to the shortage of fuel and medical supplies,” he said.

The U.N. lowered its flag to half-staff at its headquarters in New York on Monday, observing a minute of silence at its agencies around the world for its 101 staff members killed in Gaza since Oct. 7. The U.N. secretary general, António Guterres, has said it is the most U.N. staff members killed in a conflict since the organization was established in 1945.

Mr. Guterres has been negotiating with officials and colleagues to resolve the fuel situation, which has become a priority for the organization, a U.N. spokesman, Stéphane Dujarric, said.

“We shouldn’t have to negotiate for fuel,” Mr. Dujarric said.