The ongoing row between Microsoft and the European Commission over last year's landmark anti-trust ruling broke into the open yesterday when the company attacked the regulator for making inconsistent demands.

Microsoft said it was committed to complying with the ruling, but that it had been "frustrated" by the slow response to its proposals.

It also criticised the commission for offering conflicting advice on what it expected Microsoft to do.

The unusually frank remarks came after the commission gave Microsoft 10 days to comply with a key provision of the ruling, stipulating that an independent trustee should monitor Microsoft's compliance with the anti-trust penalties imposed by Brussels.

The regulator told Microsoft yesterday that it could not accept a proposal that would allow the company to veto the areas that fall under the monitor's scrutiny.

"The commission considers this veto to be unacceptable as it would compromise the trustee's ability to provide the commission with effective assistance in monitoring Microsoft's compliance," a commission spokesman said.

"Microsoft now has 10 working days to respond to the commission. Unless it agrees to the monitoring mechanism put forward by the commission, the commission intends to impose this mechanism by means of a formal decision," he added.

A Microsoft spokesman hit back: "Microsoft has provided the commission with a series of proposals for a trustee, the last of which we submitted on January 28th.

"We have been waiting for two months for feedback on this proposal and have been frustrated that the commission staff have been so slow in providing it.

"Microsoft believes that both parties are very close to an agreement."

The commission roundly dismissed Microsoft's proposal for complying with Brussels' anti-trust sanctions in another area last week. It said that Microsoft should reduce the royalties it planned to demand in exchange for providing the group's rivals with sensitive information on its Windows operating system.

It also wants Microsoft to share this information with open-source software developers, which are increasingly seen as the group's most dangerous rivals.

The group is also under fire for not properly complying with a commission order to offer a version of Windows without the MediaPlayer software.

RealNetworks, a rival, has told the commission that this new version does not function properly. - (Financial Times Service)