SK Innovation Co., South Korea's top oil refiner, said Friday it swung to a profit in the third quarter of the year on continued improvement in its lubricant oil business and reduced inventory losses.

Net profit came in at 165 billion won ($146 million) in the July-September period, a sharp turnaround from a loss of 62.5 billion won a year ago, the company said in a regulatory filing.

Sales tumbled 25 percent on-year to 12.45 trillion won over the cited period, and the company posted an operating profit of 364 billion won, compared with an operating income of 48.9 billion won a year earlier.

The strong performance was boosted by its petrochemical business, while its oil refining business suffered a setback on a fall in oil prices.

SK Innovation said it logged an operating income of 107 billion won from its refining business in the third quarter, a sharp drop from an operating income of more than 600 billion won the previous quarter.

Last year, SK Innovation swung to an operating loss of 224.1 billion won, falling into the red for the first time in 37 years.

Its earnings were hit hard in the fourth quarter as a sharp fall in oil prices hurt the value of its crude stockpiles and cracking margins.  

Shares of SK Innovation closed at 118,000 won in the Seoul bourse, up 8.76 percent from the previous session's close. (Yonhap)