Microsoft has asked three US courts to force Sun, Oracle, IBM and Novell to produce documents pertaining to the EU's (European Union's) antitrust case against the software vendor.

According to court papers filed in US District Courts in New York, California and Massachusetts, Microsoft wants to see all documents containing correspondence the companies had with the European Commission (EC), as well as the monitoring trustee and the OTR, the EC's technical advisory committee in the case.

Based on some documents the EC has already provided, Microsoft said it believes the EC had secret meetings with the technology vendors named in Friday's court papers, and that it needs access to any documents about those meetings in order to defend itself.

On Thursday Microsoft also filed a supplemental response to the EC's Statement of Objections – the formal complaints against the vendor in the case – to express its concern over its lack of access to documentation about these communications. Last week, in an unprecedented move, Microsoft posted its original response to the Statement of Objections on its website.

In a statement, Horacio Gutierrez, a Microsoft associate general counsel, reiterated the company's concerns about what it considers to be unfair treatment by the EC in providing the company access to important documents in the case.

"Our repeated requests to the EC for full and fair file access have not been successful, so we are now turning to the US courts for assistance in obtaining relevant communications between our US competitors and the EC, the technical experts it relies on and the trustee," he said.

The EC could not be reached for immediate comment on Friday.

Microsoft could face daily fines of up to €2m (about £1.37m) per day if the EC finds that the company has not complied with provisions in its March 2004 antitrust decision.