"Around 460,000 barrels per day (bpd) of crude is being refined in December and from January run rates would go up by about 2%, or about 20,000 bpd," the source told Reuters.

The source asked not to be identified due to the sensitivity of the matter.

A Hyundai Oilbank spokesman declined to comment.

The refiner said in October it would start selling VLSFO from November to meet rising demand for cleaner shipping fuels before the implementation of a global sulphur cap on marine fuels from 2020.

Hyundai Oilbank has total refining capacity of 690,000 bpd, including its 170,000 bpd condensate splitter in the southwestern city of Daesan.

(Reporting by Jane Chung; Editing by Edmund Blair)