East Libyan forces carried out air strikes around major oil ports on Saturday as they sought to regain control of the area from a rival faction, a military spokesman said.
Libyan militia of Benghazi Defence Brigades have seized control of the country's biggest oil terminals, according to the reports.
The Brigades occupied the terminals at Es Sider and Ras Lanuf after the forces of eastern Libyan National Army (LNA) led by Khalifa Haftar retreated.
The facilities are two of the largest in Libya with a combined capacity of 600,000 barrels a day.
"The attackers were armed with modern tanks," LNA spokesperson Colonel Ahmad al-Mismari said. "We lost two men. But the battle is ongoing."
The Brigades militia are allied with eastern tribes opposed to Haftar and members of the Petroleum Facilities Guard which controlled the oil ports before Haftar's takeover.
Government denies involvement
The capture of Ras Lanuf and the other three eastern oil ports in September enabled Haftar to keep up his challenge to the authority of the UN-backed government in Tripoli and demand a major role in a replacement administration.
Haftar's forces seized Zueitina, Brega, Ras Lanuf and Al-Sidra in a lightning offensive last September that dealt a major blow to the UN-backed Government of National Accord (GNA).
The Tripoli government on Friday evening denied any involvement in the latest offensive, condemning it as a "military escalation".
Rocked by chaos since the overthrow and killing of Muammar Gaddafi in 2011, Libya desperately needs to relaunch its oil exports, the backbone of its economy.
The GNA has struggled to impose its authority as it faces a multitude of battle-hardened fighters who took part in the uprising that ousted Gaddafi.
TRT World's Iolo ap Dafydd explains the strategic and economic importance of the ports.