"Oil production at the El Feel field has been suspended over the illegal closure of one of the valves at the export oil pipeline," the NOC said in a statement.
The field was also closed on 27 November due to similar reasons but soon resumed its activities.
Libya is ruled by two competing governments. The country’s east is controlled by the Libyan National Army, led by Khalifa Haftar, and its west is governed by the UN-backed Government of National Accord. Since April, the sides have been engaged in an open military confrontation.