The world's largest software maker Microsoft will invest an additional 30 million dollars in the country over the next three years to expand its research and development facilities.

Microsoft Chief Executive Officer Steve Ballmer announced the investment Thursday in a news conference on the sidelines of the Seoul Digital Forum.

He said the company will add two research facilities to its existing "Mobile Innovation Lab" in Seoul to develop Web-related technologies.

Microsoft has already invested 30 million dollars in the country.