KT Corp., South Korea's top fixed-line and No. 2 mobile operator, said Friday its first-quarter net profit fell 47.6 percent from a year earlier due to increased marketing costs on long-term evolution (LTE) service and one-off costs.

The company's consolidated net profit reached 212.6 billion won ($193 million) in the January-March period, down from 405.6 billion won a year earlier, the Seoul-based company said in a regulatory filing.

KT attributed the weaker bottom line to an increase in marketing costs to promote LTE service, and one-off costs related with the liquidation of its phone-making unit.

The LTE service, or the fourth-generation of wireless technology, enables smartphone users to access and stream data faster than the existing 3G network.

KT's marketing expenses in the three-month period reached 697.6 billion won, up 39.4 percent from 500.3 billion won a year earlier.

KT has been ramping up efforts to catch up with SK Telecom Co., the country's top mobile operator, and LG Uplus Corp in LTE service as it was the last company to introduce the fourth-generation service last year.

As of March 31, KT's smartphone subscriber base stood at 10.6 million, including 5.07 million LTE subscribers, according to the company.

KT said its operating profit plunged 36.6 percent on-year to 367.2 billion won, though revenue gained 6.7 percent to 6.1 trillion won.

Shares of KT were trading at 39,350 won on the Seoul bourse as of 10:35 a.m., up 3.01 percent from the previous session. (Yonhap News)