The UN's Mideast envoy warned Palestinians in the Gaza Strip will face a "humanitarian crisis" if their already meager electricity supply is cut further as a result of political infighting.

Israel as well as the Palestinian Authority and the Hamas movement that governs Gaza "all have obligations for the welfare of Gaza's residents", Nickolay Mladenov, the UN special coordinator for the region, told the UN Security Council on Friday.

The Palestinian Authority has been saying for weeks it would slash its payments to Israel for Gaza's electricity, and Israel announced Thursday it would reduce the power supply, which already is down to about four hours a day. No date was set.

"The UN has warned that without addressing the structural problems of Gaza's electricity supply we would face a humanitarian crisis," Mladenov said.

"How long do you think they can survive if this is further reduced to two hours of electricity per day? Who will pay the price of the ensuing violence and escalation?"

Electricity-driven drinking water is available for a few hours every two to four days, the envoy said. Hospitals are barely functioning without power, postponing surgeries and reducing cleaning and sterilisation. And for lack of irrigation, food prices are soaring.

In addition, partly operational treatment plants channel the equivalent of 40 Olympic-size swimming pools of raw sewage into the Mediterranean every day.

The Palestinian Authority of President Mahmoud Abbas quarreled with rival Hamas over fuel taxes last month, after which a power plant that Gaza relied on for nearly one-third of the territory's electricity stopped working.

READ MORE: Gaza power crisis: 'We want to end this nightmare'

Mladenov said the UN is offering emergency help to the two million Gaza residents with fuel for generators, water, medical needs and sanitation, but such reserves will run out in weeks.

"I am today warning the Security Council that unless urgent measures are taken to de-escalate, the crisis risks spiraling out of control with devastating consequences for Palestinians and Israelis alike," the envoy said.

The Gaza Strip has been under Israeli blockade for the past decade, amid violence that has taken thousands of lives in what Mladenov called "a political tug-of-war" between the Palestinian Authority and Hamas.

"In Gaza we are walking into another crisis with our eyes wide open," Mladenov said.