GENEVA: Fuel supplies in Lebanon could run out within days or weeks paralyzing hospitals and shutting down electricity across the country, UN humanitarian chief Jan Egeland has warned.

Speaking at a news conference, Egeland said: "The fuel situation is the single most worrying humanitarian crisis at the moment."

"If there's one thing that will be the most critical -- even more critical than food -- over the next days and weeks, it's fuel," he said.

Fuel supplies have been stifled by a combination of Israeli raids that have destroyed roads and bridges -- halting convoys of urgently needed relief supplies too -- and the inability to import more fuel into Lebanon.

Four hospitals in the south of the country have already run out of fuel needed for generators that were crucial for surgery and stocking drugs, Egeland said.

But a broader problem was also developing after the owners of two oil tankers chartered by the UN stopped them docking in Beirut because conditions were regarded as too dangerous, he added.