The European Commission has filed fresh antitrust charges against Microsoft for abusing its dominant position in personal computer operating systems to push its Internet Explorer web browser.

In the latest chapter in Microsoft's epic battle with Brussels, the commission accused the US software giant of thwarting competition by bundling Internet Explorer into its Windows operating system, used by nearly 90 per cent of the world's PCs.

"Microsoft's tying of Internet Explorer to the Windows operating system harms competition between web browsers, undermines product innovation and ultimately reduces consumer choice," Europe's antitrust watchdog said in a statement.

"The commission is concerned that through the tying, Microsoft shields Internet Explorer from head to head competition with other browsers which is detrimental to the pace of product innovation and to the quality of products which consumers ultimately obtain," it said.

The investigation sprang from a 2007 complaint filed by rival browser developer Opera. Other browsers available include Firefox and Google's Chrome browser, launched last year. Microsoft is about to issue a new version of Internet Explorer.

Microsoft has eight weeks to respond to the charges and can request an oral hearing to state its defence. The company faces a multi-million euro fine if found guilty of anti-competitive practices.

The European Commission and Microsoft have long clashed over the US company's practice of bundling other software such as media players into Windows.

In September 2007, Microsoft lost an appeal before Europe's second-highest court against a fine of nearly €500 million that EU regulators slapped on the company in 2004 for abusing its dominant market power.

In February 2008, the commission hit Microsoft with a further fine of €899 million for defying its 2004 ruling. Microsoft has lodged an appeal against the decision.

Microsoft has argued that bundling software gives it an incentive to innovate and the Commission's rulings would make consumers suffer.

It has also said that consumers like all-inclusive software packages that encompass features such as media players. They do not like the extra work of having to download or buy software separately, the company has said.

Last night Microsoft acknowledged receiving the latest antitrust complaint from the European Commission. The company said that it was "committed to conducting our business in full compliance with European law" and noted that it had two months to respond.

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