Powerful tribal groups loyal to Gen. Khalifa Hifter, whose forces control eastern Libya and much of the south, seized several large export terminals Friday along the eastern coast as well as southern oil fields in a challenge to the rival U.N.-backed government based in Tripoli, which collects revenues from oil production.
The critical oil industry is dominated by the National Oil Corporation, which declared that the suspension of exports would prevent the company from fulfilling contracts with international oil companies.
It warned the closure of eastern port terminals under Hifter's control would cut crude oil production by 800,000 barrels a day and estimated the country would lose $55 million in daily revenues.
Hifter's self-styled Libyan Arab Armed Forces and oil field guards have ordered five subsidiaries of the national oil company to halt exports from key oil fields and port terminals.
In a press conference, the LAAF described efforts to cripple oil production as a "major step for the Libyan people."
"The Libyan people are the ones who shut down oil ports and fields and are preventing oil exports," said spokesman Ahmed al-Mosmari, adding that it sent a "message of rejection" to militia groups defending Tripoli against a months-long siege by Hifter's forces.
The U.N. mission in Libya expressed "deep concern" over the efforts to disrupt oil production, warning of "devastating consequences." Its statement urged Libyans to "exercise maximum restraint" as international negotiations seek a resolution to the crisis.
The National Oil Corporation condemned the unrest, describing oil as the "lifeblood of the Libyan economy" and the country's only source of revenue.
"Oil facilities belong to the Libyan people and should not be used as a card for political bargaining," the chairman of the corporation, Mustafa Sanalla, said.
Tribal groups protested at the facilities, claiming the Tripoli-based government, which controls Libya's Central Bank, has used oil revenues to pay Syrian and Turkish mercenaries. They demanded that Arab countries take a "strong and clear position" in support of Hifter's eastern government and against "terrorist" militias.
The National Oil Corporation has asked the bank for greater transparency over the years, but did not comment on the allegations of corruption.
In its campaign against Hifter's forces, which are backed by Egypt, Russia and the United Arab Emirates, the embattled U.N.-backed government has turned to Turkey for troops and weapons.
Turkey's escalating involvement in the oil-rich country, including through maritime and military agreements with the Tripoli government, has rattled eastern Mediterranean countries that see Turkey as a threat to their gas and drilling rights in the region.
The warring parties and their various international backers will convene Sunday in Berlin. The summit aims to find a political solution to the conflict and halt intensifying foreign interference in the country.