BENGHAZI, Libya (AP) — Libya’s National Oil Corporation says monthly oil revenues increased by 20% to more than $1.5 billion in March, after forces loyal to a military commander captured an oil field from another militia that had closed it for three months.

NOC chairman Mustafa Sanalla said late Saturday, however, that the latest fighting in Tripoli threatens production.

Field Marshal Khalifa Hifter’s self-styled Libyan National Army captured the Sharara oil field in southwestern Libya in February and allowed the NOC to resume operations there. Earlier this month, his forces advanced on the capital, where they are battling armed groups loosely allied with a weak, U.N.-backed government.

The NOC has remained neutral in the fighting that has engulfed the country since the 2011 overthrow of Moammar Gadhafi.