Libya's National Oil Corporation (NOC) declared force majeure on exports from its Sharara oilfield on Tuesday, after production was briefly halted by an armed group just days after output had resumed following a blockade that had lasted months, reported Reuters.
An oilfield engineer told Reuters that production at Sharara had resumed again but at less than 80,000 barrels per day (bpd).
Before a five-month blockade began in January, the field had produced 300,000 bpd, equivalent to about a third of Libya's output at the time.
Almost all Libyan oil exports were stopped in January by forces based in the east of the North African nation. But military gains in recent weeks by the internationally recognised government, based in Tripoli, allowed production to resume in recent days at the major Sharara and El Feel fields.
The resumption of production was then disrupted again on Monday when a local armed group, affiliated with the eastern-based Libyan National Army (LNA), stormed the field and ordered output to stop, NOC said in a statement.
The engineer, who asked not be named, said the commander of the local armed group, Mohamed Khalifa, had allowed Sharara to reopen on Tuesday.
NOC declared force majeure on Tuesday but did not immediately comment on whether production subsequently resumed.
Oil facilities have increasingly become targets in the struggle for power in Libya since an uprising in 2011 plunged the nation into chaos and violence, pitting eastern forces against those loyal to the Tripoli government.
The LNA, which has been battling to seize control of the capital and other cities from the Government of National Accord (GNA), has retreated from many areas in the past week.
Sharara field, one of Libya's largest production areas, has been a frequent target. It had been resuming production gradually since Saturday after an almost five-month blockade of a vital pipeline to the field began in January.
During the months of blockade, NOC said an armed militia had prevented maintenance on a 16,000-barrel tank, which collapsed as a result. NOC runs Sharara in a joint venture with Spain's Repsol , France's Total, Austria's OMV and Norway's Equinor.