A view shows El Feel oil field near Murzuq, Libya, July 6, 2017. REUTERS/Aidan Lewis/File Photo

BENGHAZI, Libya/TUNIS (Reuters) - Eastern-based Libyan military forces took control on Thursday of the southwestern El Feel oilfield, their spokesman and a field engineer said.

Production was unaffected and continuing in the range of 75,000 barrels a day, the usual level, the engineer said, asking not to be named. He denied local media reports that there had been fighting inside the field located deep in Libya’s south.

State oil firm National Oil Corp (NOC), which operates the field in a joint venture with Italy’s Eni, “is concerned about the developments near El Feel oilfield and is monitoring the situation closely to ensure the safety of its staff,” an NOC representative said.

Forces loyal to commander Khalifa Haftar have waged an offensive in Libya’s south since last month. Haftar’s Libyan National Army (LNA) posted a video purporting to show their vehicles driving into El Feel. Reuters was unable to confirm its authenticity.

Separately, LNA spokesman Ahmed Mismari said his forces had allowed planes of oil firms bound for El Feel and the nearby El Sharara oilfield to resume flights.

The LNA this month imposed a ban on any flights without its permission and carried out air strikes near El Feel after a plane arrived carrying a rival commander from Tripoli, home to the U.N.-recognized government. Haftar backs a rival administration based in the east.

The LNA last week secured the El Sharara oilfield located also in the south by cooperating with state guards which had occupied it in December to press officials into financial demands.

NOC has not reopened El Sharara yet, demanding guarantees for its workers. This week it sent an inspection team by road to assess the security, but no results have been made public yet. El Sharara produced around 315,000 barrels per day until it got closed.