Armed factions allied to Libya's two rival governments fought over eastern oil ports and the main border crossing to Tunisia on Sunday, forcing closure of the two biggest oil export terminals, officials said.
In clashes reminiscent of the 2011 civil war that toppled Muammar Gaddafi, the internationally recognised government based in the east sent jets to bomb a rival force trying to seize the oil facilities of Es Sider and Ras Lanuf and started its own offensive near the Tunisian border.
The escalation comes as the United Nations is planning to resume peace talks in the coming days to try to end a struggle between former rebels who helped topple Gaddafi and now vie for power and control of oil production.
The recognised prime minister, Abdullah al-Thinni, has been based in the eastern city of Tobruk since a group called Libya Dawn seized the capital Tripoli in August after a month-long battle with rivals and set up its own government and parliament.
On Saturday, a force allied to the Tripoli-based government, whose opponents say has links to Islamists, moved along the coast to seize eastern oil facilities and fight troops of former general Khalifa Haftar loyal to Thinni.
Clashes continued on Sunday with both sides claiming progress as Thinni's forces sent jets to bomb the rival force. Al Nabaa television showed troops loyal to Tripoli loading tanks and artillery guns.
National Oil Corp, headquartered in Tripoli, shut down production at the Es Sider and Ras Lanuf ports, whose fields had produced some 350,000 barrels a day, or more than half of the country's crude output. Most staff left when the state firm declared force majeure for both ports.
Some 800 km to the west, near the Tunisian border, jet fighters under Thinni's command bombed forces loyal to the Tripoli government while Zintani tribesmen - his local allies - tried to take the Ras Jdir border crossing to Tunisia.
Omar al-Sanki, interior minister of the recognised government, said his forces had seized the border crossing. But a Libyan border official and the mayor of Zuwara, a town east of Ras Jdir, denied this.
"Our forces... are still in control of Ras Jdir," said the mayor, Hafed Juma. The Tripoli-based state news agency said air strikes had killed 15 people, among them three Egyptians, when a residential building was hit.
Tunisia said the border remained open though it advised its citizens not to cross it.
Copyright Reuters 2014.