Libya's oil company on Thursday announced an "immediate" resumption of oil exports from two of the key ports captured this week by forces opposed to the country's UN-backed unity government.
Forces led by a controversial general, Khalifa Haftar, who backs a rival administration in eastern Libya, seized four ports in the country's so-called "oil crescent" this week and handed them over to the National Oil Company (NOC).
Their capture was a blow to the Tripoli-based Govern
ment of National Accord (GNA), which relies on oil revenues and has struggled to assert its control over the country.
The seizure of Zuwaytina, Brega, Ras Lanuf and Al-Sidra oil terminals was the latest escalation of the turmoil that has gripped Libya since the 2011 revolution which overthrew longtime dictator Mummar Gaddafi.
"Exports will resume immediately from Zuwaytina and Ras Lanuf, and will continue at Brega," NOC chairman Mustafa Sanalla said in a statement. "Exports will resume from Al-Sidra as soon as possible."
Since the capture of the terminals, Sanalla has vowed to oil double production from Libya, which with an estimated 48 billion barrels holds Africa's largest oil reserves.
The news fanned concern on the international oil market about a global supply glut and overproduction that have hammered prices for more than two years.
But oil prices rebounded slightly on Thursday after tanking the previous day, although gains were capped by US stockpiles data as well as the prospect of rising output in Libya and Nigeria, dealers on world markets said.
The NOC considers itself loyal to the GNA, but also to the country's internationally-recognised parliament, which supports Haftar's forces and has refused to grant the GNA a vote of confidence.
Libya has only managed to export a few tankers of crude in recent months, with efforts to revive the industry thwarted by jihadist attacks and political turmoil.
Haftar has 'upper hand' 
"We can raise production to 600,000 barrels per day within four weeks and to 950,000 bpd by the end of the year from around 290,000 bpd at present," the NOC chief said on Wednesday.
However, this would depend on "receiving essential funds from the budget and on the oil crescent ports and the closed pipelines in the southwest being opened and kept open".
Libya has been wracked by turmoil, with rival administrations and militias vying for control over the past five years.
Under a UN-brokered accord signed in December, the GNA started work in the capital earlier this year but has since struggled to assert its authority.
And by capturing the oil ports, Haftar has consolidated his position. "Haftar now has the upper hand," said Mattia Toaldo, a Libya expert with the European Council on Foreign Relations.
"He controls most of the east and the only functioning oil terminals and he has shown that he can work with the NOC," Toaldo said.
Haftar, 73, who sees himself as Libya's saviour after driving jihadists out of most of the country's second city, Benghazi, is the most powerful backer of the eastern administration.
Parliament head Aguila Saleh on Wednesday promoted Haftar from the rank of general to field marshal.
The offensive in the oil region came as pro-GNA forces backed by US air strikes pressed a months-long campaign to expel the last Islamic State group jihadists from the coastal city of Sirte, their former North African bastion.
The jihadists overran Sirte, west of the oil terminals, in June 2015.