The European Union's top antitrust regulator is set to issue a formal ruling finding

Microsoft

(MSFT) - Get Report

guilty of breaking EU competition rules, the

Financial Times

reported in its Tuesday edition.

The software giant could face fines of up to $2.51 million a day, the paper said.

The European Commission has drafted a ruling stating that Microsoft has not fully implemented the EU's 2004 antitrust ruling, the paper said, quoting unnamed sources.

Microsoft is appealing the ruling.

That decision included an order to provide rival companies with "complete and accurate" information about Microsoft's Windows operating system, a step Brussels has said is needed for other companies to build products compatible with the Microsoft system.

"The Commission's process calls for an advisory committee meeting, so this comes as no surprise," Microsoft said in a statement quoted by

Reuters

, adding it had committed "massive resources to the technical documentation program" and had already delivered five of seven installments.

"The next two installments will be submitted on June 30 and July 18, and Microsoft is working hard to also meet those deadlines," it said.

"Given that the technical engagement is producing results and that Microsoft has complied fully with every instruction given by the Commission and the Trustee, any fine would be unjustified and unnecessary."