Updated

Libya's U.N.-backed government based in Tripoli on Tuesday urged the U.N. Security Council to block what it described as "illegal" oil sales by a rival administration based in the country's east.

The appeal comes a day after the self-styled Libyan National Army, led by Field Marshal Khalifa Hifter and based in eastern Libya, said it handed over management of vital oil terminals to a firm controlled by an interim government in the east.

The Tripoli-based government said Hifter's move was "an irresponsible action and a serious threat to the interests of the Libyan people."

"We urge the Security Council and the Sanctions Committee (on Libya) to track and block any illegal sales" by the new management of the oil facilities, it said.

The country's national oil firm tied to the internationally-recognized government said Hifter's self-styled army has "no legal authority" to hand over the oil facilities to its rival firm in Benghazi.

Libya's oil facilities "must remain under the exclusive control ... and the sole oversight of the government" in Tripoli as called for by earlier Security Council resolutions, said Mustafa Sanalla, chairman of National Oil Corp, or NOC.

"There is only one legitimate NOC, recognized by the international community and OPEC ... We are confident that the GNA and our international partners will take the necessary steps to stop all exports in breach of international law," he said.

He warned oil companies against doing oil business with "parallel institutions" and threatened of legal actions against the companies.

International Crisis Group's senior analyst for Libya, Claudia Gazzini, tweeted late on Monday that Hifter's decision not to hand over Libya's key oil exporting terminals to the National Oil Corp. in Tripoli "is dangerous" and "could re-ignite war and deepen East vs West divide."

Hifter's army said Monday it returned the oil ports of Ras Lanuf and al-Sidr to Libya's national oil company in the east. Spokesman Ahmed al-Mesmari told reporters that the national oil firm in the eastern city of Benghazi "will ensure that the contracts signed with international firms will be safe."

Hifter's forces regained control of vital oil crescent area after a militia attacked the facilities two weeks ago, forcing the National Oil Corporation in Tripoli to suspend exports and evacuate its employees.

The militia, led by Ibrahim Jadhran, a rebel commander opposed to Hifter who took part in the 2011 uprising that toppled and later killed ruler Moammar Gadhafi.

In 2013, Jadhran proclaimed himself the guardian of Libya's oil crescent, including the ports of al-Sidr, Ras Lanouf and Brega, which represent about 60 percent of Libya's oil resources.

Sanalla, the NOC chairman, said Jadhran's actions cost Libya more than $100 billion over three years. Jadhran eventually lost control of the oil crescent to Hifter's forces in 2016.

Libya descended into chaos following the 2011 uprising. The country is now split between rival governments in the east and west, each backed by an array of militias. Hifter is allied with the east-based administration that is at odds with the U.N.-backed government based in the capital, Tripoli.

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Associated Press writer Samy Magdy in Cairo contributed to this report.