Microsoft has released a test version of its latest web browser, the success of which will be critical for reviving the software giant’s reputation for security.

The beta version of Internet Explorer (IE) 7 is now available for download from the company’s website, www.microsoft.com. However, users have been advised that the product should not yet be used in "mission-critical environments".

IE has lost market share in the last year to rival browsers such as Firefox, a product that is available to download for free on the internet and which trades heavily on its reputation as a more secure alternative.

IE still accounts for around 90 per cent of the browser market, maintaining its long-held dominance, but Microsoft is aware that consumers are becoming more conscious of cybercrime, in part because of a Government-backed initiative in the UK to highlight the dangers.

There has also been talk that Google, Micoroft's arch-rival, which has links with Mozilla, the group behind Firefox, could also launch its own browsing software.

In response, Bill Gates, Microsoft’s billionaire founder, has made it clear that security has become the priority for a company that has been criticised for concentrating too much on making its products easy to use as crimes such as identity theft and "phishing" – where criminals steal personal details from online PCs – are rapidly growing.

This week Microsoft was hit by the news that another virus has targeted its near-ubiquitous Windows operating platform. Experts have warned that the Blackworm virus could destroy vast amounts of information by overwriting files stored on PCs when it is triggered on Friday.

Hackers have also tended to target the Microsoft browser because it is still used by the majority of internet users and therefore gives access to the widest range of targets.

Microsoft, which is widely regarded as a follower of internet fashions rather than a pioneer, now appears keen to learn from its upstart rivals. The latest version of IE incorporates tabs allowing users to flick between web pages within the same window, similar to those used on rival browsers such as Firefox and Opera. A box that allows users to access a range of search engines without leaving the page they are viewing is also included.

Microsoft said: "Internet Explorer 7 helps keep your information safe by alerting you to potential phishing sites – sites that look legitimate but actually are designed to capture your personal information."

The browser will display a warning if the user strays onto a site that is known to be used by criminals to collect personal information and will caution users about sites that have aroused suspicion. It will also make it easier for users to see whether the site they are visiting has a valid SSL certificate, which makes it harder for fraudsters to set up fake banking sites, for example, designed to trick people into revealing passwords and credit card numbers.

Tim Callan, group product marketing manager at the internet security company Verisign, welcomed Explorer 7's security features but said they have been a long time coming. "The browser manufacturers have been slow to act," he said. "We’re very excited by what they’re doing now, but I think that maybe they could have done it sooner."

Microsoft is encouraging web technicians to download Explorer 7 and test the way it works with different kinds of website. The beta version is available to anyone who wishes to use it, but it may not yet be compatible with all sites. A full version is expected later this year.

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