Libya's National Oil Company (NOC) announced on Sunday the suspension of oil production from two major fields.
According to a statement released on social media production was interrupted after an armed group shut down the valves delivering the crude.
The statement added that the closure is causing losses of 330,000 barrels per day and a daily loss of around 32 million euros.
Since the fall of Muammar Gaddafi's regime in 2011 that Libya has been involved in more than a decade of civil unrest.
A parallel government sworn in by Libya's parliament and seeking to oust the ruling executive in Tripoli was sworn in last Thursday further aggravating the institutional crisis in the country.
According to the NOC, the armed group led by a certain Mohamed al-Garj had already closed the valves several times between 2014 and 2016.