SEOUL, May 13 (Reuters) - SK Innovation Co Ltd, the owner of South Korea's top refiner SK Energy, said on Thursday refining margins are likely to gradually improve in the second quarter due to demand recovery backed by easing COVID-19 impact.

The company posted an operating profit of 503 billion won ($444.88 million) in the January-March quarter, compared with an operating loss of 1.8 trillion won in the same period a year earlier. ($1 = 1,130.6400 won) (Reporting by Heekyong Yang and Joyce Lee; Editing by Christopher Cushing)