Libya's oil exports are set to rise to 800,000 barrels per day in January, a senior source at the National Oil Corporation (NOC) told Reuters on Thursday.

This compared to exports of around 500,000 bpd in December. The NOC expects to deliver between 40 and 45 cargoes of crude oil this month, the source said.

Libya's oil output is rapidly returning to pre-war levels and provided the biggest increase to OPEC supply last month, when production from member states rose to the highest since 2008.

The main reason oil output is still below pre-war levels of around 1.6 million barrels per day is a lack of power generation, which is preventing some fields from restarting or reaching full capacity, according to the NOC.

"I think output will return faster than planned, the only obstacle is power generation. Some (power generators) have been damaged or stolen in many places," the NOC source said.

Libya has awarded contracts to buy its prized, sweet oil to a selection of oil majors and trading houses, breaking from a policy of restricting sales to refiners in the region.

Trading houses including Glencore and Swiss-based trading giants Vitol, Gunvor and Trafigura together will receive around 70 cargoes this year.