Libya is gradually restarting production at the El Sharara oil field, the country’s largest, two field engineers and an oil industry source said on Aug. 8, after unknown gunmen had blocked a pipeline.

“Production has restarted,” one of the engineers said.

There was no immediate official comment from state oil firm NOC.

The field, south of Zawiya port in western Libya, was shut late in July by an armed group. It produces about 290,000 barrels per day (bbl/d), accounting for a quarter of Libya’s oil production.

That shutdown prompted NOC to declare force majeure on loadings of the crude grade.

Prior to the shutdown, Libya was producing 1.2-1.3 million bbl/d, a six-year high for the OPEC member which has struggled to return to a pre-civil war capacity of 1.6 million bbl/d.