A group of computer and telephone companies charged yesterday that Microsoft was using "extortion" in its battle with Netscape Communications for dominance in selling browsers for the World Wide Web. Mr Edward Black, head of the Computer and Communications Industry Association, said Microsoft, whose operating system is used on 90 per cent of personal computers, was telling computer makers they must use its Web browser "or else", and that its stance had "elements of extortion."

The association also filed a brief in support of the Justice Department, which claims the software company is abusing its monopoly by insisting computer makers highlight Internet Explorer, Microsoft's Web browser, in order to obtain Windows, Microsoft's operating system.