Microsoft has poured scorn on Mozilla's download figures for its Firefox browser. Amy Barzdukas, a Microsoft general manager in chage of IE, said that the announcement that the software had reached a billion downloads was "interesting math".

Firefox claimed it hit that figure at the start of July, but Barzdukas sayd "It's an interesting number and I have not seen the math [but] how many internet connected users are there? 1.1 billion, 1.5 billion, something in that area".

Firefox has 22% of the market, meaning that everyone who has ever downloaded it would have to have downloaded it an average of five times for that figure to be accurate. "As with any marketing statement, I'd encourage people to be somewhat sceptical about large number claims", said Barzdukas.

She also spoke about the recent high-profile campaign from websites to persuade users to upgrade from IE6, saying: "I don't think anybody would argue that (IE6 provides a good web browsing experience)".

However, she refused to talk about Microsoft's dallainces with the European Commission over the bundling of IE with Windows. "We have posted our proposal. Nothing is final until it's final, and there are a number of questions about how (a) ballot would be designed. That's something we'll continue to work on with the commission".