SK Innovation Co., South Korea's leading refiner by sales, said Monday its net losses widened in the first quarter from a year earlier due mainly to foreign-exchange losses.

Net losses deepened to 97.62 billion won ($71 million) in the first quarter from 51.95 billion won in the year-ago period, the company said in a statement.

"A weak won, which drove up import prices of crude oil and decreased equity gains from SK On, weighed on the quarterly bottom line," a company spokesperson said.

The dollar rose to an average of 1,328.45 won in the first quarter from 1,275.58 won a year ago, according to data from the Bank of Korea.

SK Innovation holds an 89.52 percent share in car battery unit SK On, which suffered a sales decline amid slowing demand for electric vehicles.

As for the second quarter, SK Innovation expects refining margins will remain steady, helped by the OPEC+ member nations' continued oil output cuts and rising demand for gasoline during the summer peak season.

Saudi Arabia and Russia lead the Organization of the Petroleum Exporting Countries+ member countries.

In response to slowing car battery sales, the company will flexibly adjust output volumes in its global facilities in the coming quarters, the statement said.

Operating profit jumped 67 percent to 624.74 billion won in the March quarter from 374.99 billion won a year ago due to robust refining margins and high oil prices.

Sales fell 1.5 percent to 18.86 trillion won from 19.14 trillion won during the same period. (Yonhap)