Libyan firefighters battled a major blaze at the country's second-largest oil refinery Tuesday after a drone strike ignited a gasoline storage tank at the Zawiya facility west of Tripoli, according to the company operating the site.

On Monday night, a large gasoline reservoir in Zawiya caught fire and collapsed after it was "struck by a drone while another drone fell near a second tank without causing casualties", Hamdi al-Bishti, head of the Brega Oil Company which runs the refinery, told AFP.

Firefighting efforts and the cooling of adjacent tanks to prevent the fire from spreading were underway since the night of the strike.

Bishti said it was difficult to fully contain the fire given the tank was filled with gasoline.

The National Oil Corporation (NOC) said the tank contained about 4.5 million liters of gasoline and declared a state of emergency Monday night.

Authorities have yet to identify the perpetrators, days after similar drone attacks targeted a naphtha reservoir and a water desalination plant over the weekend.

"It's a heinous act," said Bishti. "We came close to tragedy."

Libya has the most abundant oil reserves in Africa but has been beset by violence and instability since the overthrow of Moammar Gadhafi in 2011.

Two governments are currently vying for power: the U.N.-recognized administration in Tripoli led by Prime Minister Abdul Hamid Dbeibah and a rival in the east, backed by Khalifa Haftar.

The reservoir is part of the second-largest oil refinery in Libya, with a refining capacity of 120,000 barrels per day.

Brega said it stored at the site significant amounts of diesel, kerosene, gasoline and liquefied petroleum gas (LPG) – petroleum derivatives intended to fuel power stations in western Libya.