Libya’s state-run National Oil Corporation (NOC) announced on Monday that militia fighters shut down the Sharara oil field, the largest in the country, plus another vital oil field at el-Feel.

The attacks reduced Libya’s oil production by at least 330,000 barrels per day, an unwelcome development at a time when Russia’s invasion of Ukraine is generating worldwide anxiety about oil supplies.

The Sharara field was shut down on Thursday after gunmen closed one of its main valves. A similar action was launched against el-Feel shortly afterward. On Sunday, the NOC invoked force majeure to cancel contracts for oil from the two occupied facilities.

Libya is a member of the Organization of Petroleum Exporting Countries (OPEC) and holds Africa’s largest oil reserves.

NOC chief Mustafa Sanallah demanded legal action against the “planners, executors, and beneficiaries” of the shutdown, including punitive actions that would serve as “deterrent measures” against future attacks. Another oil official in Tripoli told Reuters that local tribal leaders are negotiating with the militia to let production resume at the oil fields.

Libyan officials seemed reluctant to clearly identify the “gang” behind the attacks, but their comments suggest it is the ironically-named Petroleum Facilities Guard (PFG), or possibly one of its splinter groups.

The PFG is a paramilitary force aligned with eastern warlord Khalifa Haftar. The PFG seized control of Sharara and other oil fields on several previous occasions, most recently in December 2021. The PFG usually makes demands for money or other concessions to its troops, who are theoretically employed as security for the same oil fields they keep seizing. 

The militia shut down Sharara and three other fields in December after salary payments were delayed to its personnel, for example, and then demanded additional concessions such as the construction of a new road from its mountain headquarters city of Zintan to the Tripoli area. The official who spoke to Reuters indicated the group that shut down Sharara and el-Feel over the weekend was based out of Zintan.

The PFG released a statement on Monday claiming an “outlaw” group was behind the oil production shutdowns. The statement expressed confusion at why these outlaws would cripple Libya’s oil production amid the industry chaos caused by the Russian invasion of Ukraine, and insisted it has no current grievances with the NOC, because “the salaries of January were disbursed to all employees without delay.”

The NOC on Monday identified the leader of the armed group as Mohamed Bashir al-Garg, a commander of forces normally charged with guarding oil facilities. Al-Garg reportedly said he took action because of the “dire living conditions” his people have been subjected to.

The NOC shut down six of Libya’s oil terminals for part of the weekend due to bad weather, angering Energy Minister Mohammed Oun, who frequently clashes with NOC leadership. Oun said the port shutdowns were unnecessary and a “violation of national security.” He reportedly told Bloomberg that Libya’s oil production dropped approximately 25 percent from 1.2 million barrels a day on Wednesday.

One of the six terminals, the port of Zueitina, has been the scene of tribal protests for several months. The protesters managed to shut the port down in January, ostensibly because they were enraged by the Tripoli government using oil revenues to hire foreign fighters. Tuareg tribesmen threatened to shut the Shahara field down last week by blocking the roads leading to it.

The United Nations and United States on Monday called for all blockades on Libya to be lifted. Stephanie Williams, special Libya adviser to U.N. Secretary-General Antonio Guterres, said “freedom of movement around the country is a basic right” and “blocking oil production deprives all Libyans from their major source of revenue.”

U.S. Ambassador to Libya Richard Norland also called for the oil blockade to be “lifted immediately.”

Libya is dealing with a national political crisis that could be greatly exacerbated by instability in oil production. The eastern-based “House of Representatives” (HoR) installed a new interim government on Thursday, including a new prime minister, but current Prime Minister Abdul Hamid Dbeibah refuses to relinquish power until elections are held. Dbeibah’s supporters regard the HoR’s actions as a coup attempt. Armed forces are assembling across the country, possibly laying the groundwork for a new civil war.