"There continues to be no water for the vast majority of the population in Gaza," UNRWA spokesperson Juliette Touma told reporters in New York in a video conference from Amman.

The World Health Organization earlier said that water, fuel and electricity would run out within 24 hours, warning that Israel had intensified the blockade on the enclave after the deadly attack by the Palestinian group Hamas on October 7.

"We're talking about two million people in the Gaza Strip who do not have water and water is running out and water is life. Life is running out of Gaza," said Touma.

"We are very concerned about the spread of waterborne diseases if water continues not to be available in Gaza, because we do know that people are resorting to dirty water sources, including wells," she said.

The Israeli bombardment of Gaza, launched in retaliation for the Hamas attack, has killed at least 2,750 people, including hundreds of children, according to local authorities.

UNWRA used to provide food assistance to almost 1.2 million people in Gaza, but since October 7, no supplies from the organization or any other UN agency have arrived in the Hamas-controlled enclave, which is completely isolated.

Touma said that the fear was being felt among UNRWA's own workers in the Gaza Strip.

"We feel that the levels of desperation and frustration and exhaustion among our staff specifically increases by the hour," she said.