UN Secretary-General Antonio Guterres called for Hamas to release all hostages and for Israel to allow humanitarian aid into Gaza, warning that the Middle East was "on the verge of the abyss."

"Gaza is running out of water, electricity and other essential supplies," Guterres said in a statement.

UN stocks of food, water, medical supplies and fuel in Egypt, Jordan, the West Bank and Israel "can be dispatched within hours," he continued, adding that staff "need to be able to bring these supplies into and throughout Gaza safely, and without impediment."

And he called for Hamas to release hostages "immediately" and "without conditions."

"Each one of these two objectives are valid in themselves. They should not become bargaining chips and they must be implemented because it is the right thing to do," said Guterres, who claimed it was his duty to make both appeals "in this dramatic moment, as we are on the verge of the abyss in the Middle East."

Israel declared war on Hamas last Sunday, a day after waves of the militant group's fighters broke through the heavily fortified border and shot, stabbed and burned to death more than 1,400 people, most of them civilians.

The subsequent relentless bombing has flattened neighborhoods and left at least 2,670 people dead in the Gaza Strip, the majority ordinary Palestinians.

With AFP