South Korea's major airlines plan to suspend or reduce their flights bound for Japan as the number of passengers visiting the country is declining, company and industry sources said Sunday.

Asiana Airlines Inc. plans to suspend its twice-a-day flights linking the southeastern port city of Busan to Osaka starting on Feb. 21. It recently received approval from the transportation ministry for the flight suspension, according to the sources. 

An Asiana Airlines official said that the decision was made due to "declining profits" from Japan-bound services. 

Korean Air Lines Co. is also following suit by stopping its flights between Incheon and Shizuoka from March 30. The country's largest flag carrier is currently providing flights three times a week between the two areas. 

"We will suspend the service for the time being due to a fall in the number of passengers," a company official said. "The service could be resumed when demand picks up."

The decisions came after local airlines cut back on their Japan-bound flights last year as the number of passengers traveling to the neighboring country dropped amid worries over radioactive contamination and strained Seoul-Tokyo diplomatic relations. 

Korean Air stopped flying between Incheon and Nagasaki in March, while reducing the number of flights bound for Okayama, Niigata and Komatsu in October. Asiana Airlines also curtailed its flights from Incheon to Sendai and Shizuoka in October.

In 2013, Korean Air saw the number of passengers using its Japan-bound flights decline 15.4 percent on-year to 3.91 million.

Asiana Airlines also posted a 5.5 percent drop. 

The sharp fall resulted in worsening profits for the two major flag carriers. Korean Air and Asiana Airlines logged 17.6 billion won and 11.2 billion won, respectively, in operating loss last year. (Yonhap)