A rocket hit a storage tank at the eastern Libyan oil of port Es Sider as armed factions allied to competing governments fought for control of the country's biggest export terminal, officials said on Thursday.
Clashes were also reported from Sirte, a city west of Es Sider, killing up to 19, residents said. No more details were immediately available.
Es Sider and its adjacent Ras Lanuf terminal have been closed since a force allied to a rival government in Tripoli moved east trying to take them.
"A tank was hit but the damage is limited," said an official from a security service allied to the internationally-recognised government, now operating from eastern Libya. He said there were heavy clashes in the Ben Jawad area west of Es Sider where he said some of the rival forces were based.
He accused opponents of having shot at the port from boats which they had tried to dock at Es Sider. "The air force destroyed three boats which were attempting to seize the port," he said.
Ismail al-Shukri, spokesman for the rival force, denied this, saying war planes belonging to the other side had bombed the port. "Our forces are progressing from all directions towards Es Sider port," he said.
An oil ministry official said the tank was still on fire. Smoke could be seen on pictures posted on social media websites and described as showing the port. No more information was immediately available.
The fighting had reduced Libya's crude output to 352,000 barrels a day, a spokesman for state-owned National Oil Corp (NOC) said. Only the Brega, Sarir, Messla and offshore operations were still producing, he said. Es Sider and Ras Lanuf ports were processing an estimated 300,000 bpd.
Libya has had two governments and parliaments since a group called Libya Dawn seized the capital Tripoli in August by expelling a rival faction, installing its own prime minister and forcing the recognized cabinet to operate out of the east with the elected House of Representatives.
Western powers fear the North African country might break up as former rebels who helped oust Muammar Gaddafi in 2011 now use their guns to control the OPEC oil producer.