Microsoft said it plans to post on Thursday confidential documents on the Web used in its defense as it is fighting the threat of European Commission anti-trust fines reaching up to 2 million euros ($2.4 million) a day. The documents are to be posted at 1800 GMT at the following link, including an exchange of letters between its chief executive, Steve Ballmer, and EU Competition Commissioner Neelie Kroes.

"Transparency is vitally important in what can be a very opaque process in Brussels. We've decided to open this up so people can understand the issues," said Horacio Gutierrez, Microsoft's European associate general counsel.

The Commission says Microsoft failed to comply with remedies it imposed in 2004 for the company's violation of anti-trust rules. Specifically, the Commission says Microsoft failed to produce required documentation in a form that worked.

Microsoft is opening defense documents it sent in response to a statement of objections from the Commission, minus business secrets, but has no plans to post the Commission's objections.

The Commission considers those objections confidential and had little to say.

"We are carefully analyzing (Microsoft's) reply and after they have had the opportunity to present their arguments at the oral hearing we will decide whether or not to impose a daily fine," Commission spokesman Jonathan Todd said.

The hearing, as yet unscheduled, will be closed.