The Libyan National Army (LNA), commanded by Khalifa Haftar announced on Wednesday that it had retaken the Libya's 70,000-barrel-per-day (bpd) El Feel Oil Field from armed groups loyal to the Government of National Accord (GNA).
The National Oil Corporation said earlier on Wednesday that air strikes had halted production at El Feel as LNA retaliated after forces aligned to the GNA in Tripoli took control of the field.
The LNA drove out the rival group and was securing the field, its spokesman, Ahmed Mismari, said on his Facebook page.
The fighting reignited a conflict for control of large oilfields in southwestern Libya between competing military alliances that are also battling on the outskirts of the capital, Tripoli.
"There have been air strikes at the gates of the El Feel oilfield and inside a housing compound at the field used by NOC personnel," NOC Chairman Mustafa Sanalla said in a statement.
"Production will remain shuttered until military activity ceases and all military personnel withdraw from NOC's area of operations."
The LNA said its jets had launched air strikes "at the perimeter of El Feel oilfield targeting the positions of armed groups that attacked the field".
The country's oil production has been repeatedly disrupted in recent years by conflict and blockades but is currently relatively stable at about 1.25 million bpd.
El Feel is operated by Mellitah Oil and Gas, a joint venture between the NOC and Italy's Eni. An engineer at the field said production was 70,000 bpd before the stoppage.
Haftar's forces have controlled El Feel and the nearby El Sharara oilfield, Libya's largest, since February, when they swept through the south before launching an offensive on Tripoli in April.
The campaign for Tripoli quickly stalled, though fighting between rival forces continues on the outskirts of the capital.