The UN human rights chief said on Thursday that widespread outbreaks of disease and hunger seemed "inevitable" in Gaza after weeks of Israeli assault on the densely populated Palestinian enclave.

Speaking at an informal briefing to states at the UN in Geneva after visiting West Asia, Volker Turk said the depletion of fuel would have a "catastrophic" impact across Gaza. It would lead to the collapse of sewage systems, and healthcare and end the scarce humanitarian aid being supplied.

"Massive outbreaks of infectious disease, and hunger, seem inevitable," Turk, the UN High Commissioner for Human Rights, said.

The World Health Organisation has warned of "worrying trends" in disease spread in Gaza, saying there had been an unusually large number of cases of diarrhoeal disease in the enclave, where bombardments and a ground operation have disrupted the health system, access to clean water and caused people to crowd into shelters.