South Korean regulators searched the offices of Microsoft's subsidiary there yesterday in connection with a probe into the computer giant's bundling of instant messaging software with Windows.

Officials from the Korean Fair Trade Commission (KFTC) came to Microsoft's offices to collect information for their investigation, which is expected to take several days, Microsoft spokeswoman Stacy Drake said.

The antitrust investigation into Microsoft's bundling practices started about two years ago, a source familiar with the investigation said. The KFTC started its probe after a complaint from Daum Communications, a South Korean Web portal company, The Korea Times reported Thursday.

"Microsoft has been and will continue to cooperate fully with the KFTC as they carry out their inquiry," Drake said.

In addition to complaining to the South Korean regulator, Daum filed a private lawsuit against Microsoft in April for allegedly violating South Korea's antitrust law.

The South Korean investigation comes the same week that Microsoft appealed against a ruling by the European Commission that it broke European competition law. The Commission fined Microsoft $598 million earlier this year and limited its business practices. Microsoft is appealing that ruling.

Additionally, Japanese authorities raided Microsoft's offices in that country in February as part of an investigation into possible anticompetitive practices in the software maker's dealings with Japanese personal computer makers