|A tanker sits docked at an oil facility in rebel-held Al Brega in Libya [Getty Images]
Libya's oil output is down by half as a consequence of political unrest in the country, the International Energy Agency says.
That figure matched a 50 per cent fall in production claimed by the North African country's National Oil Company with the industry in chaos as international energy companies have scrambled to evacuate their staff.
Libya is one of the world's leading oil powers, usually producing around 1.6 million barrels a day, mostly for the European market.
Oil industry analysts and investors are watching the situation closely amid fears that further unrest in OPEC member states in North Africa and the Middle East could send crude prices spiralling higher.
Oil prices reached $120 last week but eased after Saudi Arabia pledged to increase production to meet any shortages.
"This is not good news for suppliers in the market but at the same time it is very comforting that Saudi Arabia showed their readiness to make up," Fatih Birol, IEA chief economist, told the Reuters news agency.
However, Libya's oil industry showed signs of recovery on Monday with a tanker terminal at the eastern port of Tobruk reported to be operating at "100 per cent".
Rajab Sahnoun, an official with the Arabian Gulf Oil Co., said a tanker bound for China with capacity for one million barrels was being loaded at Tobruk. An Italy-bound tanker is also waiting to begin loading in the coming days, he said.
"The terminal is working at 100 percent," Sahnoun told The Associated Press news agency.
Another Agoco official, Ali Faraj, said a pipeline connecting the port to the eastern oilfields of Sarir and Misla was operating normally. The company's production of around 220,000 barrels a day had been largely unaffected, Faraj said.
European Union Energy Commissioner Guenther Oettinger said Libyan leader Muammar Gaddafi, who is struggling to contain a popular uprising that threatens to sweep him from power, had lost control of most of the country's oil and gas fields.
Many facilities were now controlled by regional families or provisional regional leaders opposed to Gaddafi's authority, Oettinger told a meeting of EU energy ministers.
"They have taken over control, they have taken away control from Gaddafi," he said.
But oil industry sources told Reuters the ports of Marsa el Bregam Es Sider and Zuetina remained at a virtual standstill, affected by both reduced production and bad weather in the Mediterranean.