Libya's crucial oil exports from its production heartland ground to a halt Monday in a financial showdown between the country's rival political administrations.
The crisis has slashed production, previously estimated at one million barrels per day, by 850,000 bpd, said the National Oil Corporation run by the Tripoli-based Government of National Accord (GNA).
The NOC said all exports have been suspended from the oil crescent in northeast Libya after operations were frozen at the terminals of Al-Hariga and Zweitina.
Exports from the region's two other ports, Ras Lanuf and Al-Sidra - seized from a rival militia by military strongman Khalifa Haftar's self-styled Libyan National Army (LNA) - were already suspended on June 14.
The NOC declared force majeure on crude oil loadings at the ports, a status that frees parties to a contract from their obligations due to circumstances beyond their control.
The suspension amounts to a $67.4 million a day loss in Libya's heavily oil-dependent public revenues, according to the NOC.
Libya has been wracked by chaos since the 2011 Nato-backed uprising that toppled and killed long-time dictator Moamer Kadhafi, with two rival authorities vying for control.
The LNA recaptured the terminals in June after they were seized by armed groups led by militia leader Ibrahim Jadhran, who had controlled them from 2011 to 2016.
Haftar's forces said they would hand the installations and their revenues to an eastern administration that rivals the UN-backed GNA in the capital.
It warned that "no tanker will be allowed to dock" in the ports without permission from a Benghazi-based rival NOC.
But the GNA last week urged the United Nations to block any "illegal" oil exports, and the NOC in Tripoli said Monday it was the "only recognised Libyan entity" responsible for oil production and exports.
"Despite our warnings of the consequences and attempts to reason with the LNA general command, two legitimate allocations were blocked from loading at Al-Hariga and Zweitina this weekend," said NOC chairman Mustafa Sanallah.
In the statement, the NOC called on Haftar's forces to lift their blockade, saying losses to the public purse "since the attack on Al-Sidra and Ras Lanuf... by Ibrahim Jadhran is more than $650 million".
Libya produced 1.6 million bpd of oil before Kadhafi's ouster in February 2011. Production fell by about 20 percent after the revolution, before recovering to one million bpd by the end of 2017.