The field, which had been producing about 315,000 barrels per day (bpd), was closed after a group of state guards and tribesmen seized it, making financial and other demand. NOC declared force majeure, a waiver on its contracts.
NOC, based in Tripoli, in the west of Libya where the internationally recognised government is based, has said it will not reopen the field without a new security arrangement and once other conditions are met, such as ensuring its workers are safe.
Libyan forces loyal to a commander based in the east of the politically divided nation took control of the field last week, after holding negotiations with the state guards and tribesmen.
"We call on NOC to lift force majeure," Naji al-Maghrabi, the eastern-based commander of the state oil guards which were appointed to protect the field, said in a statement posted online.
A spokesman for the eastern military confirmed the handing over of the field to the oil force.
There was no immediate comment from NOC.
It was not immediately clear if handing over security to security guards under the control of an eastern-based commander would meet NOC's demands.
The eastern forces launched an offensive in mid-January to secure the southern oilfields, which include El Sharara.