The National Oil Corporation (NOC) condemned the attack on Zella oilfield, southwest Libya, in which two guards and a soldier were killed and four others kidnapped, according to a Saturday statement.
The Islamic State group claimed responsibility for the attack in its Aamaq news agency later on Saturday.
The Zella field belongs to Zueitina Oil Company, which pumped 19,000 barrels per day on average in the last quarter of 2018 across all its fields.
The attackers struck an entrance gate to the field, which lies near the town of Zella, about 760 kilometers southwest of the capital Tripoli, before fleeing, according to locals.
Chairperson of the NOC Mustafa Sanalla said workers at the field were safe and facilities were not damaged; however, he warned that continuing instability in the country could affect 95 percent of its oil production.
The Islamic State has been active in Libya in the turmoil since the overthrow of Muammar Qaddafi in 2011. The militant group took control of the coastal city of Sirte in 2015 but lost it late in 2016 to local forces backed by US airstrikes.
In the last two years, the group has targeted three state institutions in Tripoli, home of the UN-backed government of national accord led by Prime Minister Fayez al-Sarraj.
Saturday’s assault took place as the LNA, which is allied to a rival administration in eastern Libya, mounts an offensive to control Tripoli.
The NOC announced on Sunday that oil revenues reached $11.87 billion in April, with an increase of 22 percent compared to March.