Gunmen have stormed the Al-Mabrook oilfield in central Libya, a spokesman for state-run National Oil Corp (NOC) said on Wednesday.

Armed factions allied to two rival governments are fighting for control of Libya four years after the ousting of leader Muammar Gaddafi.

"Unknown gunmen stormed the Mabrook oilfield last night," NOC spokesman Mohamed El Harari said, without providing details.

Operations at the field, located south of Sirte, were closed following clashes which closed the Es Sider oil port in December.

France's Total, which operates the field with NOC, said it had already withdrawn staff from the site.

Sirte is home to members of the Ansar al-Sharia Islamist group. The region has seen fighting as armed groups vie for control of the Es Sider and Ras Lanuf oil ports.

Opec member Libya's oil output has fallen to around 350,000 barrels per day, the latest data shows, from 1.6 million pumped during Gaddafi's reign. - Reuters