"Microsoft's tying of Internet Explorer to the Windows operating system harms competition between Web browsers, undermines product innovation, and ultimately reduces consumer choice," the European Commission said in a statement released Saturday.
The EC, a European Union body, claimed that Explorer controls 90% of the Web browser market and that its built-in presence on Windows "distorts competition on the merits between competing Web browsers insofar as it provides Internet Explorer with an artificial distribution advantage which other Web browsers are unable to match."
Alternate browsers, such as Firefox and Apple's Safari, have failed to dent Microsoft's share of the browser market despite generally positive user reviews.
"The commission is concerned that the ubiquity of Internet Explorer creates artificial incentives for content providers and software developers to design Web sites or software primarily for Internet Explorer, which ultimately risks undermining competition and innovation in the provision of services to consumers," the EC stated in a document it formally refers to as a Statement of Objections.
The EC said it delivered the document to Microsoft last week.
The commission said it could impose fines on Microsoft or force the company to ship versions of Windows in Europe that do not include Explorer.
In response, Microsoft said it's studying the EC's objections. "We are committed to conducting our business in full compliance with European law," the company said in a statement.
Microsoft and European trustbusters have butted heads numerous times. Last year, the EC hit the company with a record $1.35 billion antitrust fine, claiming that Microsoft had failed to make available to rivals documentation needed to create products that are interoperable with Windows.
The EC ordered Microsoft to make the documentation available under "reasonable terms."
Previously, the EC also ordered Microsoft to ship a version of Windows that did not include the Windows Media Player. The version has not proved popular with European PC users, according to Microsoft.