A group of the world's largest technology companies complained to the European Commission on Thursday that Microsoft was guilty of anticompetitive practices.
The European Committee for Interoperable Systems (ECIS), which includes IBM, Nokia, Oracle and RealNetworks, claimed Microsoft was hampering competition in the software market.
ECIS said in a statement: "We are at a crossroads. Will one dominant player be permitted to control those conditions, or will the rules that guarantee competition on the merits prevail, to the benefit of all?"
ECIS called on the EC to take action against Microsoft. It cited the software giant's refusal to use the OpenDocument standard or release details of its .doc, .xls and .ppt file formats, which prevents the makers of other productivity suites from being fully interoperable with Microsoft Office.
Simon Awde, chairman of the group, said: "ECIS deeply regrets that strong antitrust law enforcement appears to be the only way to stop the sustained anti-competitive behaviour of Microsoft."
A spokesperson for the EC told journalists the Commission was examining the complaint.
But Microsoft downplayed the significance of ECIS' move.
A Microsoft spokeswoman said: "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."
Microsoft also accused ECIS of bias and hiding behind legal processes: "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. We will respond quickly and comprehensively to any requests for information from the Commission on this complaint but no such requests have been received so far."
Last week, Microsoft and the EC traded blows over the 2004 antitrust ruling, with Microsoft accusing the EC of disregarding evidence and failing to follow due process. This enraged the Free Software Foundation which said Microsoft's attack was outrageous.