GENEVA: The U.N. humanitarian office said on Friday it would cost an estimated $1.2 billion to meet the needs of 2.7 million people in the Israeli-occupied Gaza Strip and 500,000 people in the West Bank until the end of the year.

On Oct. 12, the U.N. Office for the Coordination of Humanitarian Affairs (OCHA) had initially appealed for $294 million in funding to support nearly 1.3 million people.

"The situation has grown increasingly desperate since then," said OCHA spokesperson Jens Laerke.

Aid supplies to Gaza have been choked since Israel began bombarding the densely populated enclave in the wake of attacks by Hamas gunmen in southern Israel on Oct. 7, with aid organisations saying it is nowhere near matching the needs of its residents.

In addition to killing thousands, heavy bombardment by Israeli forces has hindered aid workers' ability to deliver desperately needed supplies.

"There's been a high number of casualties reported, as well as the reported use of explosive weapons with wide area effects in some of the most densely populated areas in Gaza," said Liz Throssell, spokesperson for the Office of the UN High Commissioner for Human Rights (OHCHR).

"We have serious concerns that the principles of distinction and proportionality are not being respected by both sides."

In its revised appeal for funding that will be published on Monday, OCHA said it would outline the need for food, water, health care, shelter, hygiene and other urgent priorities.

"We urge donors to promptly make resources available for the response," Laerke said.

"Our ability to ease the suffering of the Palestinian population will depend on adequate funding, safe and sustained access to all people in need, wherever they are, sufficient flow of humanitarian supplies, and - importantly - fuel."