In the case of Microsoft, I sincerely regret that the company has still not put an end to its illegal conduct, she added. It is now more than two years since the Commission’s March 2004 decision that found Microsoft to be in violation of the EU’s antitrust rules by abusing its dominant market position.

The Commission has followed up on its earlier threats to fine Microsoft for failing to provide complete and accurate interface specifications that would allow competing technologies to interoperate with Windows.

The 1.5m euro ($1.9m) daily fine was back-dated to December 16, 2005, and was not as high as the 2m euros ($2.5m) a day originally threatened, but Kroes signaled that its significance should not be underestimated.

This is the first time ever, in the 49-year history of the European Union, that the Commission has had to fine a company for failure to comply with an antitrust decision. I hope that it is also the last, she said.

Kroes also announced that if Microsoft continued to fail to comply with its obligations the potential fine would be raised to 3m euros ($3.8m) per day from July 31.

At issue are the 64 protocols required by the Commission to enable Microsoft competitors to interoperate with Windows. Microsoft has already submitted 32 of them to the Commission’s satisfaction, while 17 have been sent back for revision, and a further 15 have not been submitted.

Microsoft said it intends to appeal the fine, maintaining that it does not reflect the efforts the company had gone to in order to meet EC requirements. We do not believe any fine, let alone a fine of this magnitude, is appropriate given the lack of clarity in the Commission’s original decision, said Brad Smith, Microsoft VP and general counsel.

Smith admitted that the company would have to receive and read the Commission’s decision before deciding the specific ground for its appeal, but maintained that the company had shown good faith to meet the requirements, once the Commission clarified those requirements in April.