Libya was once a major OPEC oil producer in North Africa, and pumped about 1.6 million barrels per day, or almost two percent of world supply, before an uprising against Qaddafi’s autocratic rule in mid-February.

Rebels have prised the east of the country from his grip, and they sold their first tanker full of crude to US refiner Tesoro in April, but production has since ground to a virtual halt due to concerns over the security of the oilfields.

“We don’t think the oil infrastructure has been particularly badly damaged physically .... The current estimate is that in the east they can start pumping within three or four weeks,” said a British Foreign Office diplomat.

He was responding to a question on the resumption of oil exports from the east, where the bulk of Libya’s oilfields lie, should Qaddafi be toppled or step down. Recent comments by rebel leaders make it seem unlikely they would restart exports sooner.

Britain is one of the leading nations in a coalition conducting air strikes against Qaddafi armor and troops under a UN mandate to protect civilians, and there are close contacts between British officials and the rebel leadership.

Oil is Libya’s main export and the rebels are desperate for cash to sustain an armed uprising that has failed to make to make much headway against Qaddafi loyalists in recent months.

East Libyan crude exports could hit 355,000 bpd in the short term, US bank Goldman Sachs said in a report on Wednesday.

Richard Jones, the deputy head of the International Energy Agency, said the loss of Libyan oil output since February represented a greater disruption to global oil supply than the aftermath of Hurricane Katrina in 2005.

Jones said the initial disruption to oil output in Libya happened at a “fortuitous” time for European oil refiners as many were closed for maintenance.

“Now we’re going into the summer driving season, those refineries which have returned to operation are about to ramp up their production.”

Jones said the market was facing a possible shortfall of 1.8 million barrels per day for the remainder of June and 1.7 million for the next quarter.

As well as releasing stocks in the wake of the Hurricane in the Gulf of Mexico in 2005, the agency also made oil available during the 1990 Kuwait crisis.