Smoke and flame rise from an oil storage tank that was set on fire amid fighting between rival factions at Ras Lanuf terminal, Libya in this handout picture released on June 18, 2018. (Reuters photo)
Clashes between rival groups in Libya's key oil export ports have caused output to drop by nearly half, the head of the National Oil Company said on Wednesday.
"Production has seen a reduction by 450,000 barrels per day, plus 70 million cubic feet of natural gas, equivalent to $33 million in sales based on market prices," Mustafa Sanallah told AFP via email.
The Ras Lanuf and Al-Sidra terminals have been closed since Thursday when armed groups attacked oil facilities held by forces loyal to military strongman's Khalifa Haftar in eastern Libya.
Haftar's self-styled Libyan National Army has since launched an offensive to push the militias out of the area, with clashes causing "catastrophic damage", according to the NOC.
Before the output cut, Libya had been producing just over one million barrels of oil per day.
The NOC chief, who was in Vienna for an OPEC meeting on Tuesday, was revising upwards an earlier NOC estimation that put production losses at 400,000 bpd.
On Monday, the NOC said fires caused by the clashes destroyed two crude tanks -- reducing storage capacity at the Ras Lanuf terminal by 400,000 barrels.
"Maintenance teams are still dealing with the aftermath of the blaze and are trying to ascertain the extent of the damage to the terminal," Sanallah said.
The armed groups that launched Thursday's attacks are loyal to rebel leader Ibrahim Jadhran.
Jadhran's Petroleum Facilities Guard controlled the terminals for years following the 2011 ouster and killing of Moamer Kadhafi -- but they were eventually forced out by the LNA in September 2016.
Libya's economy relies heavily on oil, with production at 1.6 million barrels per day under Kadhafi.
His NATO-backed 2011 ouster saw production fall to about 20 percent of that level, before recovering to more than one million barrels per day by the end of 2017.