The European Commission has again criticised Microsoft's response to a 2004 antitrust ruling, opening up the possibility of further fines for the company.

In March 2004, the Commission fined Microsoft and ordered it to provide its competitors with information allowing them to develop workgroup server software interoperable with the Windows desktop operating system. It then fined the company again last July for failing to provide that information on time.

The Commission has sent Microsoft another statement of objections, saying it considers the interoperability information Microsoft has offered is still incomplete, said Jonathan Todd, Commission spokesman on competition issues. In addition, Microsoft is charging its competitors too much for that information: it does not justify the price tag put on it because it is not innovative, he said.

Microsoft has four weeks in which to respond to the statement of objections, after which it may face further daily fines for non-compliance with the antitrust ruling.

Even as Microsoft and the Commission dispute whether Microsoft is in compliance with the ruling, another court is considering whether Microsoft should have to comply at all.

The European Court of First Instance, in Luxembourg, is still considering Microsoft's appeal against the Commission's March 2004 ruling that Microsoft abused its monopoly in desktop operating systems to exploit markets for workgroup server and media player software.

At that time, the Commission ordered Microsoft to pay a fine of €497 million (then around US$600 million), ship a version of Windows without media player software, and publish the server software interoperability information disputed in today's announcement.

Peter Sayer, IDG News Service, contributed to this report.