South Korea's top mobile carrier SK Telecom Co. said Monday its fourth-quarter net profit rose 39.1 percent from a year earlier due mainly to increased competitiveness in Internet businesses.

Net income reached 660.6 billion won ($606 million) in the October-December period, compared with a profit of 474.7 billion won for the same period the previous year, the company said in a regulatory filing.

For the whole of 2017, net profit came to 2.65 trillion won, up 60 percent from 2016.

Operating profit edged up 2.8 percent on-year to 310.4 billion won in the fourth quarter and sales moved up 3.3 percent on-year to 4.49 trillion won in the October-December period.

For the whole of 2017, operating profit came to 1.53 trillion won in 2017, up 0.06 percent from a year earlier.

Sales came to 17.52 trillion won in 2017, up 2.51 percent from 2016.

SK Telecom said the on-year increase in sales -- the first increase in three years -- was attributable to the rising number of subscribers to Internet and Internet protocol television services.

The country's No. 1 mobile carrier said its service subscribers numbered 32 million, up 600,000 from a year earlier. Subscribers for its long-term evolution network services came to 1.79 million, taking up 75.7 percent of combined users.

SK Telecom said its affiliate SK Broadband Co. -- responsible for media businesses -- also saw its sales increase 3.6 percent on-year in 2017 to 3.5 trillion won due to the rising number of clients for IPTV services.

The earnings report was released before the local stock market opened. (Yonhap)