Libya's Zawiya refinery has returned to pre-shutdown output levels at around 60 percent of capacity and is running Brega crude oil, a senior Libyan oil official said.

The 120,000 barrels-per-day (bpd) refinery and port re-opened at the weekend after being shut down by opponents of the General National Council (assembly) for a few days.

The refinery, which supplies the capital and western Libya with petrol, cannot run at full capacity, because the El Sharara oilfield, which feeds it, has been closed since March by various local tribes.

Negotiations are continuing between Tripoli and a federalist rebel group that has blocked Libya's two largest oil ports for the past nine months.

The Opec member's interim oil minister was optimistic about the first phase of a deal to reopen two ports and expected a return to Libya's normal pre-blockade output level if no new disruptions pop up.

"The oil sector can reach goals of 1.4 million bpd on average in normal operating conditions if there are no (other)strikes that would lead to obstructions at fields and ports by strikers outside the oil sector," acting Oil Minister Omar Shakmak told Reuters.

He added that he could not give a timetable for the resumption as the oil ministry was not involved in the negotiations with Ibrahim al-Jathran, the leader of the federalist group blocking the ports.

"The oil and gas ministry is not involved in this," he said, clarifying comments from an interview on Wednesday that he could not discuss politics.

He said the state oil protection force had so far given clearance only to restart exports at the Hariga port.

The Zueitina oil port was still closed on Thursday despite the deal to reopen it along with Hariga, several Libyan oil officials said, as a separate group of citizens was also trying to negotiate new jobs. - Reuters