Mozilla, the non-profit group that has become one of the biggest thorns in Microsoft’s side, will ramp up its assault on the world's largest software developer tomorrow when it releases a new version of its popular Firefox internet browser.

Firefox, which has been given considerable support by a number of Microsoft competitors, already accounts for up to 30 per cent of the market in some territories, Mozilla claims.

Developed by an "opensource" community made up of thousands of volunteers, including engineers on loan from Google, it has become the greatest rival of Microsoft’s market leading Internet Explorer.

Firefox is currently being downloaded by around 350,000 users a day, Mozilla says. The launch of Firefox 2.0, which Mozilla expects to accelerate the product's uptake, come just days after Microsoft released Internet Explorer 7, an updated version of its own browser, to mixed reviews.

Mike Schroepfer, vice president of Mozilla Corporation, told Times Online: "We’re not too concerned about Microsoft beating us in terms of release dates. In fact we’re quite amused that IE7 shipped only in English where Firefox will be released in around 30 languages."

Mozilla insiders have also been critical of what they see as Microsoft’s tendency to ship products that are not yet ready for the market. "From what I’ve seen so far of Vista [the forthcoming upgrade of Windows, Microsoft’s near ubiquitous operating system] Microsoft is still shipping to dates, rather than when products are ready," Mr Schroepfer said.

In line with its forebears, Firefox 2.0 will trade heavily on its claim to be more secure than Microsoft’s browser. It will include new protections against "phishing" – or internet identity theft by cybercriminals – through a tool that will tell users when they meet websites that are suspected forgeries, designed to capture personal details.

Other new features will include an "in-line" spell checker, that will highlight spelling mistakes users make online and more tightly-integrated search functions.

The updated search features in Firefox, which allow users to "manage" their choices of search engine, highlight in part the way that Mozilla earns tens of millions of dollars from companies such as Google and Yahoo!, by promoting their sites.

Mozilla was formed from the remnants of Netscape, the broswer company that lost its dominant market position to Internet Explorer in the 1990s. It commercial success has already forced the group to divide into two parts, the non-profit Mozilla Foundation and a commercial arm, the Mozilla Corporation, in order to operate under American laws controlling charities.

The new Firefox browser will be available here

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