The World Health Organization chief said on Sunday it will be all but impossible to improve the "catastrophic" health situation in Gaza even as the board passed an emergency WHO motion by consensus to secure more medical access.

Palestinian officials have also described a disastrous health situation in Gaza, where Israel's assault has left most of the population homeless, with little electricity, food or clean water, and a medical system facing collapse.

The emergency action, proposed by Afghanistan, Qatar, Yemen and Morocco, seeks passage into Gaza for medical personnel and supplies, requires the WHO to document violence against healthcare workers and patients and to secure funding to rebuild hospitals.

"I must be frank with you: these tasks are almost impossible in the current circumstances," WHO Director General Tedros Adhanom Ghebreyesus said. Still, he commended countries for finding common ground, saying it was the first time any U.N. motion had been agreed by consensus since the conflict began.

Tedros told the 34-member board in Geneva that medical needs in Gaza had surged and the risk of disease had grown, yet the health system had been reduced to a third of its pre-conflict capacity.

Mustafa Barghouti, a Palestinian politician who heads the Union of Palestinian Medical Relief Committees with 25 teams working in Gaza, said: "Half of Gaza is now starving."

He said 350,000 people had infections including 115,000 with severe respiratory infections and lacking warm clothes, blankets and protection from the rain.

He said many were suffering from stomach complaints because there was little clean water and not enough fuel to use to boil it, risking outbreaks of dysentery, typhoid and cholera.

"To add insult to injury, we have 46,000 injured people who cannot be treated properly because most of the hospitals are not functioning," he said.