Antitrust investigators from the EC (European Commission) are holding meetings with key Microsoft officials at the company's US headquarters to discuss whether it is complying with the antitrust ruling of March 2004, an EC spokesman confirmed today.

Officials from the team working on Microsoft's case have been in Redmond since Monday to hear the company's arguments about why it believes it has complied with the 2004 ruling. In that ruling the EC ordered the company to offer a version of Windows without its Media Player and ensure that rival developers could interoperate with its workgroup server software.

A spokesman for Competition Commissioner Neelie Kroes, the EU's top antitrust official, said the meeting would focus on the issue of Microsoft's compliance and the technical documentation it provided on the communications protocols for the workgroup server software.

The monitoring trustee, an independent expert chosen by Microsoft to assess the company's compliance with the ruling, is also attending the meeting, the spokesman, Jonathan Todd, said. Todd added that the meeting was planned over a month ago and was not an emergency session following the company's offer last week to grant access to the source code for Windows server software.

Last Wednesday, Microsoft offered to grant access to the source code underlying the communications protocols on its workgroup server software as part of efforts to respond to EC criticism of the documentation it provided.

However, Microsoft's rivals strongly criticised the move and said they had no interest in gaining access to the underlying code.

The EC also downplayed suggestions that the move might allow Microsoft to avoid the €2m (about £1.37m) fine the company faces if it does not comply, saying it was the "quality", not the "quantity" of the documentation that counted.