Russian and other foreign mercenaries have entered a key oil field in southern Libya, the conflict-hit country’s National Oil Corporation said Friday.

The mercenaries drove into Al-Sharara oilfield in a convoy of vehicles late Thursday, the NOC said in a statement on its website, expressing “great concern.”

After a months-long suspension, Al-Sharara — under the control of forces loyal to eastern military strongman General Khalifa Haftar — resumed operations at the start of June, only to halt work again three days later at the instruction of those forces.

Plunged into chaos by the 2011 NATO-backed uprising that toppled and killed its longtime leader Moamer Kadhafi, oil-rich Libya has two rival administrations.

Haftar’s forces, which are backed by Russia, Egypt and the UAE, launched an assault in April 2019 to wrest control of the capital Tripoli from the UN-backed Government of National Accord.

But Haftar’s fighters withdrew from the southern outskirts of the capital — and the entire west of the country — earlier this month, after a string of battlefield defeats to the Turkish-backed GNA.

Moscow denies any involvement in the presence of Russian mercenaries in the conflict, despite a UN report in May alleging fighters from the Wagner paramilitary group, reputedly close to President Vladimir Putin, are on the ground.

NOC chairman Mustafa Sanalla condemned the latest intervention in Al-Sharara, located in the Oubari region some 900 kilometres (550 miles) south of Tripoli.

“Libya’s oil is for the Libyan people, and I completely reject attempts by foreign countries to prevent the resumption of oil production,” he said.

“We do not need Russian and other foreign mercenaries in Libyan oilfields whose goal is to prevent oil production,” said Sanalla.

“We need patriotic, professional, and independent security forces who will facilitate the resumption of oil production for the benefit of all the Libyan people, with revenues allocated fairly and transparently across the whole of Libya.”

When in operation, Al-Sharara produces 315,000 barrels per day — nearly one third of Libya’s crude output.

Oil exports are the source of almost all the state’s revenues, and Libya has the biggest proven crude reserves in Africa.

Al-Sharara is run by the Akakus company, a joint venture between NOC, Spanish oil giant Repsol, France’s Total, Austria’s OMV and Norway’s Statoil.