The United Nations aid agency in Gaza says it has run out of food in its distribution centres, which feed more than 700,000 Palestinians.

Gaza's only power plant has again shut down because of a fuel shortage, as the result of Israel's blockade.

Israel closed the border into Gaza more than a week ago, in response to cross border attacks by Palestinian militants.

The senior liaison officer with the UN Relief and Works Agency, Saahir Lone, says the implications of the embargo are grave for hundreds of thousands of Palestinians.

"If this interruption to food lasts more than a few days, the most vulnerable people in that society, of which there are many now ... the implications are very serious," he said.