United Nations Secretary-General Antonio Guterres pushed on Monday for a full humanitarian cease-fire between Israel and Palestinian militants Hamas instead of a temporary truce, as the "humanitarian catastrophe in Gaza is getting worse by the day."

Egyptian, Qatari and U.S. negotiators closed in on an extension of a four-day truce in Gaza that expires on Monday, Egyptian security sources said, amid growing global pressure to roll over a deal which has paused seven weeks of fighting.

"The dialog that led to the agreement must continue, resulting in a full humanitarian cease-fire, for the benefit of the people of Gaza, Israel and the wider region," Guterres' spokesman Stephane Dujarric said in a statement.

"The United Nations will continue to support these efforts in every possible way," he said.

Guterres again called for the hostages held by Hamas to be released immediately and unconditionally, Dujarric said.

The United Nations has scaled up the delivery of humanitarian aid to Gaza over the past four days during the truce and sent aid to some northern areas of the coastal enclave that had been largely cut off for weeks, Dujarric said.

"But this aid barely registers against the huge needs of 1.7 million displaced people. The humanitarian catastrophe in Gaza is getting worse by the day," he said.