Antitrust regulators from the 15 European Union countries have unanimously backed the European Commission's negative ruling against Microsoft, a Commission spokeswoman said today.

The advisory committee meeting of the 15 national regulators broke up early Monday, spokeswoman Amelia Torres said: "The meeting is over. The member states have unanimously backed the Commission's draft decision," she said.

The Commission's decision remains secret. However, people close to both Microsoft and the European Commission said the ruling calls for Microsoft to offer PC manufacturers a version of Windows without Media Player, the video and audio playing software, attached.

The draft ruling, which is likely to be made final on March 24 – unless the two sides reach a settlement before then – also demands that Microsoft reveals undisclosed code in Windows, in order to allow makers of rival software for servers to compete fairly with Microsoft's server software.

A fine of up to 10 per cent of Microsoft's global annual sales will be decided in the coming days. People following the case say it could be anywhere between €100 million ($122 million) and €1 billion.