SK Innovation, owner of the country's biggest oil refiner SK Energy and electric vehicle (EV) battery maker, said it is in the early stage of talks to review the process.

"We are currently reviewing various strategic options to secure financial health and finance our new businesses, but we have not yet decided whether to sell SK Lubricants or how much of a stake we will sell," an official at SK Innovation told Reuters.

SK Lubricants, wholly owned by SK Innovation, produces base oil and finished lubricant products. It could be valued between 3 trillion won ($2.53 billion) and 4 trillion won, Korea Economic Daily reported.

In July, SK Innovation reported a second-quarter operating loss of 440 billion won ($367 million), taking its first-half losses to 2.2 trillion won. A year earlier, it posted an operating profit of 494 billion won in the second quarter.

($1 = 1,184.1200 won)

(Reporting by Heekyong Yang; Editing by Kim Coghill)