Some of Microsoft's biggest rivals have lodged a new complaint with the European Commission. This time, the concern is the software company's forthcoming Office launch and the worry that the company's business practices are shutting out competitors.

A coalition called the European Committee for Interoperable Systems (ECIS), which includes IBM, Nokia, Oracle, RealNetworks and Red Hat, announced that it had made a formal complaint to the Commission over a "range of products present and future." The reference to future products is understood to include Microsoft's Vista desktop operating system, due for release later this year.

One example of the issues raised in the complaint is Microsoft's refusal to disclose interoperability information for its Office suite, a lawyer representing ECIS said. By refusing to provide data such as the file formats for .doc, .xls, and .ppt documents, the company prevents other applications suites such as OpenOffice and StarOffice from achieving full compatibility, according to attorney Thomas Vinje, acting for ECIS. "This has crucial implications for Linux on desktops," Vinje said.

ECIS said it was calling on the Commission, which is the European Union's anti-trust watchdog, to end Microsoft's harmful business practices, which it said threaten to "deny enterprises and individual consumers real choice among competing software products."

The company's behaviour served to "reinforce Microsoft's existing monopolies and extend its market dominance into a range of existing and preannounced future product areas," ECIS said. The groups members also include Sun Microsystems, Corel, Linux vendor Linspire and browser vendor Opera Software.

While the complaint is separate from the Commission's ongoing anti-trust case against Microsoft, ECIS said in a statement that the complaint involved "bundling and interface nondisclosure practices similar to those the Commission declared illegal in its 2004 decision" against Microsoft. It called for the limits on "Microsoft practices established in European anti-trust law" to be "rapidly and broadly enforced."

Microsoft dismissed the latest charges. "We have come to expect that as we introduce new products that benefit consumers, particularly with the kind of breakthrough technologies in Office 12 and Windows Vista, a few competitors will complain," the company said.

"ECIS is a front for IBM and a few other competitors who constantly seek to use the regulatory process to their business advantage. When faced with innovation, they choose litigation," it continued.

The company will respond "quickly and comprehensively" to any request from the Commission for information about the complaint, although so far it has received none, it said.

A spokesman for EU competition commissioner Neelie Kroes said the Commission would "examine the complaint carefully".

The Commission is not obliged to launch an official investigation even if companies complain about a rival's business practices.