LONDON, UK: Microsoft Corp's next version of Windows is stirring fresh complaints of anticompetitive behavior from rivals who say the new version of the operating system gives unfair advantage to Microsoft's Internet Explorer browser, the Financial Times reported.

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"Our initial review suggests this is a blatant use of the Windows operating system to change the market dynamics of browser usage," Mitchell Baker, chairperson of Mozilla, developer of open-source Firefox browser, told the paper.

No-one at Microsoft could immediately be reached for comment.

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Opera, the Norwegian browser company, echoed Mozilla's complaints about Windows 7, the paper said.

Microsoft had earlier said users will be able to turn off key programs like Internet Explorer, making it easier to use other browsers.

Microsoft is scheduled to respond to European Union antitrust regulators in a hearing next month on charges it sought to thwart rivals by tying the company's Web browser to its Windows operating system.