Daum Communications, South Korea's largest Internet portal, filed a complaint against Microsoft Corporation over the U.S. software giant's planned release of its new operating system Windows XP.
In the complaint, Daum said Microsoft's bundling of a variety of application software, including instant messaging, Internet phone service, and digital pictures to Windows XP constitutes an unfair business practice.
Windows XP, the latest version of Microsoft's flagship product, is scheduled for widespread retail release on October 25.
The spokesman for Microsoft Korea declined official comment on the issue.
The Fair Trade Commission said it will launch an official investigation into the case soon.
Daum controls 20 percent of Korea's instant messaging market. Microsoft accounts for more than 90 percent of Korea's operating system market.
Daum is accusing Microsoft of using its monopolistic position to force local PC makers to buy Windows XP and other software features.