Forces loyal to eastern Libyan commander Khalifa Haftar took control of key oil ports in Ras Lanuf, Es Sider and Brega on Sunday, said Ahmed al-Masmari, a spokesman for the forces.
But an official from the force that previously controlled the ports, the Petrol Facilities Guard, said there was still fighting at Ras Lanuf.
Masmari said clashes were continuing at another oil port, Zueitina, and around the nearby town of Ajdabiya.