Libyan authorities on Wednesday said a damaged pipeline linking the Sarir oil field to terminal in the port of Tobruk was causing a serious leak into the desert.
The damage comes at a time of political impasse that had crippled the country's oil industry.
The tussle to control Africa's largest oil reserves has long been a feature of Libya's protracted civil war.
What's behind the spill?
The Arabian Gulf Oil Company, the operator of the pipeline, estimates that some 22,000 barrels a day are being lost from the leak, which began on Tuesday. It posted footage of the spill and said an attempt to stop it was underway.
The operator — an affiliate of the state-run National Oil Corporation — blamed a lack of maintenance and cited a budgetary delay.
Libya has been in turmoil since a NATO-backed uprising in 2011 that ousted dictator Moammar Gadhafi. He was later killed.
The country has since become divided between rival governments, and many of the country's oil fields and facilities have been forced to close.
One, in the east, is backed by military commander Khalifa Hifter, while a UN-supported administration claims power from the capital, Tripoli.
Last month saw the most serious fighting in Libya since 2020, when Hifter's forces waged a campaign to try to take the city. He had backing in that effort from mercenaries from Russia's Wagner Group.
The country's eastern-based rival parliament in February named Fathi Bashagha, a former interior minister and air force pilot, as prime minister. His rival, Tripoli-based Prime Minister Abdul Hamid Dbeibah, has refused to stand down and has said he will only hand over power to an elected government.
Edited by Mark Hallam