Fires caused by clashes between fighters of the Islamic State of Iraq and the Levant and security forces at Libya's biggest oil ports have spread to five oil storage tanks that were still burning on Wednesday.
At least nine troops were killed and more than 40 wounded in fighting around the perimeter of the area on Monday and Tuesday, said Ali al-Hassi, a spokesman for the security forces.
Guards recovered bodies of 30 ISIL combatants, and also captured two tanks and other vehicles from the armed group, he said.
Four of the fires were at the port in Es Sider and one at Ras Lanuf. Two blazes were triggered by shelling from ISIL and the fire spread to three more.
Hassi said the Petroleum Facilities Guards were still in control of Es Sider and Ras Lanuf ports but clashes continued.
Mohamed al-Manfi, an oil official in eastern Libya, said each of the oil tanks was estimated to contain 420,000 to 460,000 barrels of oil.
Es Sider and Ras Lanuf have been closed since December 2014. They are located between the city of Sirte, which is controlled by ISIL, and the eastern city of Benghazi.
Libya is split between political factions and armed groups competing for power and for the country's oil wealth, four years after the revolt that toppled the leader Muammar Gaddafi.
Oil output has dwindled to less than one-quarter of a 2011 high of 1.6 million barrels per day.
READ MORE: The Battle for Libya's Oil
ISIL has profited from a security vacuum to expand its presence, though it has not taken control of oil installations in the country.
The armed group attacked guards at Es Sider in October, but its offensive this week appeared to be a more concerted assault on the ports.
Mustafa Sanalla, chairman of the National Oil Corporation (NOC) in Tripoli, said he hoped the violence would "lead political leaders on all sides in Libya to understand the magnitude of the threat we face".
"We need to unite against this common enemy, not tomorrow or next week, but now," he said in a statement.
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