Libya's National Oil Corporation says unidentified assailants have abducted workers at a facility belonging to an oil field, hampering daily production.

Saturday's statement by the NOC says the assailants kidnapped four staff members working at Station 186 of the Sharara oil field, adding that only two have since been released. It was not immediately clear if foreign workers were among those abducted.

Oil wells nearby have been shut down and workers evacuated as a precautionary measure, the NOC said. It estimates losses to daily production will be around 160,000 barrels per day. It added that it was in touch with authorities and closely monitoring developments.

Libya has descended into chaos following a 2011 uprising that toppled longtime ruler Moammer Gadhafi.