Libya plans to remove protesters who have seized eastern ports vital for lucrative oil exports within the next few days, Prime Minister Ali Zeidan has said.

But he did not say whether force would be used, telling Libya's Al-Ahrar news channel that he did not want the country to plunge into civil war.

Since the summer, a group of heavily-armed demonstrators has occupied three eastern oil ports which together accounted for 600,000 barrels per day of exports, in a bid to force the Tripoli government to give it political autonomy.

"In the next days we're about to clear the ports of the protesters unless they leave them," Zeidan said.

He added that tribal leaders were still holding talks to try to end the standoff peacefully. When pressed for details he replied: "I cannot discuss state affairs on television."

Tribal chiefs have so far failed to persuade the group's leader Ibrahim Jathran to end the siege of the ports, which has contributed to a halving of oil production since August, when the protests began, and put a huge strain on the budget.

The government has warned it will be unable to pay public salaries if the demonstrations continue. Several deadlines set by Zeidan have passed without any action.

Authorities are struggling to rein in militias and tribesmen who helped topple Muammar Gaddafi in a Nato-backed uprising in 2011.

NON-CONFIDENCE VOTE

Zeidan accused the Muslim Brotherhood and another Islamist group in the General National Congress (GNC) assembly of trying to topple his cabinet by pursuing a parliamentary non-confidence vote against him.

On Tuesday, former militiamen briefly stormed the GNC building and fired shots in the air to try to force a non-confidence vote against Zeidan.

Libya's transition to democracy has been paralysed by infighting between the government and rival factions inside the GNC, but even Zeidan's opponents agree there is no one to replace him for now.

When asked whether he was worried he might lose a confidence vote, Zeidan said: "I would be happy if the vote went through. I don't cling to power."

Zeidan also said the security situation in the restive south had calmed after days of fighting between rival militias in the main city of Sabha, which the government has blamed on Gaddafi loyalists.

Libyan war planes attacked targets to regain control of an air base near Sabha, the defence ministry said on Saturday.

"There is no fighting any more," Zeidan said. "The air base is under government control." - Reuters