The chairman of Libya's state-oil firm National Oil Corp (NOC), Nuri Berruein, has resigned, NOC spokesman Mohamed El Harari said on Friday.
He gave no reason for the resignation, Al Arabiya reported.
Libya's oil sector has been crippled by 10 months of protests at major oilfields and exports ports reducing output to little over 200,000 barrels a day from 1.4 million in July when strikes started.
The protests are driven by a mix of militias, tribesmen and state employees making political and financial demands.