Libya's National Oil Corporation (NOC) has evacuated staff from both the Sidra and Ras Lanuf terminals due to armed clashes in the area.
It said the loss in oil production is around 240,000 barrels per day (bpd) and a planned tanker berthing at Sidra was postponed on Thursday.
NOC bosses are following the situation closely.
"The NOC board has called for individuals or political groups who attempt to capture Libya’s oil installations, blockade production, or attempt to make NOC a bargaining chip, to be brought to justice," it said.