At least 150 have died in two weeks of fighting between militias and pro-government forces in Tripoli and Benghazi.
The government said fighting between rival militias in Tripoli was to blame for the oil depot blaze. Mohamed al-Harrai, a spokesman for the Libyan National Oil Co., told the BBC firefighters Monday had the blaze under control, but were forced to give up when fighting erupted in the area.
NOC said the violence made it difficult to feed the domestic gasoline market, leaving many filling stations without fuel.
The interim government in Tripoli issued a plea for international help with controlling the violence.
International forces intervened in a civil war in 2011 that left longtime leader Moammar Gahdafi dead. Once one of North Africa's top producers, Libya has struggled to keep oil output close to pre-war levels above 1 million barrels per day.