Dubai: Libya’s biggest oilfield was said to stop producing, leading to a 20 per cent decline in crude output from the country with Africa’s largest reserves.

The Opec nation is pumping 560,000 barrels a day, according to a person familiar with the matter who isn’t authorised to speak to the media and asked not to be identified. The North African country was pumping 700,000 barrels a day, Mustafa Sanalla, chairman of state-run National Oil Corp., said on March 22. The pipeline carrying crude from Sharara, Libya’s biggest field, to the Zawiya refinery stopped operating, according to another person who asked not to be identified.

It wasn’t clear why the pipeline was shut. The NOC didn’t respond to calls seeking comment.

Clashes among rival armed groups in early March led to the closing of two of the nation’s biggest oil export terminals, forcing a number of other fields to halt production. The ports have since reopened. Libya pumped as much as 1.6 million barrels a day before a 2011 uprising led to the ouster of former leader Moammar Qaddafi and a breakdown in central authority that stunted oil production.

“The important question for the market will be whether this turns into a lengthy disruption or not,” Richard Mallinson, an analyst at Energy Aspects Ltd. in London, said by email. “The political and security situation remains deeply unstable and so I am not surprised to see Libyan output continue to fluctuate on these kinds of issues.”

Sharara, in western Libya, had been producing 221,000 barrels a day, the NOC said March 21. Libya is one of the smallest members of the Organisation of Petroleum Exporting Countries.