When the EC found Microsoft guilty of abusing its monopoly position last year, it ordered the company to pay a 497m fine, and to offer a version of Windows without Media Player and open up its software APIs to rival firms. It expected these measures to be quickly adhered to.

But the EC now feels that Microsoft has not done enough to satisfy the commandments, and that the company should stop dragging its feet over complying with the EC's wishes. The EC is able to fine Microsoft as much as five per cent of its daily turnover for every day it is not compliant with the judgement.

An EC spokesman told the BBC: "Ms Kroes said that the Commission expects the decision adopted in March 2004 to be complied with urgently and in full, and she added that unless this was the case that the Commission would be obliged to take formal steps to ensure compliance."

The Competition Commission is still not convinced that Microsoft's MediaPlayer-free version of its software is "technically up to standard" or that Microsoft has done enough to open up its server software to rival companies.