Agoco, an oil firm based in rebel areas, said on Tuesday it was now only pumping oil to Tobruk in the far east of Libya after Muammar Gaddafi's forces retook Ras Lanuf, where it has facilities.
Arabian Gulf Oil Co (Agoco) management board member Hassan Bulifa also told Reuters that output from the firm's fields was holding steady at one-third of its normal production levels.
Agoco had previously said it was producing about 130,000 barrels per day (bpd), compared to about 400,000 bpd before a rebellion against Gaddafi's rule erupted in mid-February.
"We stopped pumping oil to Ras Lanuf. Production at our fields is still about one-third of normal output but now all the oil is being pumped to Tobruk," he said. "We have a tank farm, a storage facility, there."
Bulifa said it would take about three weeks to fill up the storage available at the current rates of production. On March 10, he had said storage could be filled in two or three weeks.
Agoco, owned by the state's National Oil Corp (NOC), is based in Benghazi where rebels have set up a National Libyan Council that is working to oust Gaddafi.
"So far the fighting has had no effect really. Agoco has seen no damage to any of its oil facilities," Bulifa said.
Agoco has facilities at Ras Lanuf, retaken during an advance by Gaddafi's forces along a coastline that is dotted with oil towns such as Es Sider, Ras Lanuf and Brega.
Rebels said Gaddafi's warplanes bombed storage tanks owned by state-owned Ras Lanuf Oil and Gas Processing Company (RASCO), while Libyan state television blamed it on rebels. Facilities in Es Sider were also hit.
"We are part of the transitional national council and (on Monday) they appointed an adviser to the council who will be responsible for the oil industry," he said.
He named the adviser as Ali Tarhouni, describing him as an academic and an economist. Agoco was coordinating with Tarhouni, Bulifa said.
"There are no plans (for new exports) this month. As far as next month goes, we will have to coordinate with the national transitional council adviser. We have to set a new policy in coming days," he said.
Agoco has said it was making arrangements to market oil directly to foreign buyers instead of via its state-owned parent but did not have any shipments lined up for the rest of March.
It loaded a tanker for China's Sinopec at the end of February at its Tobruk terminal and had said another for Austria's OMV was next. Those deals were contracted by NOC's marketing division.
Libya usually produces 1.6m bpd of oil but output has been slashed. Under normal conditions, it is the world's 17th largest producer and the third largest in Africa, and it holds the continent's largest crude oil reserves.
Agoco is involved in seismic, exploration and production work for oil and gas and operates fields that include Sarir, Nafoora and Misla fields in the Sirte basin. It has said the Hamada field it operates in the west of Libya was not operating.