Popular browser Firefox has snatched more than 20 per cent market share during two separate weeks in October, according to new statistics.

Net Applications, which compiled the data, claimed that Mozilla’s web browser crossed the significant threshold for the week starting 5 October, and, since then, has continued to float around the 20 per cent mark.

At the same time, Microsoft’s Internet Explorer has lost ground. It now holds around 71 per cent market share in the hotly contested browser wars. Whether that will change when the firm brings out IE8 remains to be seen, however.

Mozilla released Firefox 3 into an enthusiastic market in June this year. Meanwhile, IE8 is expected to land sometime in January 2009.

Opera also recently brought an updated version of its browser into play, and internet kingpin Google even got in on the act in September with the launch of Chrome.

In related news, Mozilla released its new private browsing porn mode feature to testers fiddling with beta versions of Firefox 3.1 earlier this week.

Microsoft spurted out a second beta of IE8 in late August that included the controversial “InPrivate Browsing” tool. The feature, when enabled, will switch off cookies, browsing and search history, and it won't save form data and passwords. In addition, it will automatically clear the cache at the end of the browser session.

Now, the latest Firefox 3.1 beta comes loaded with a similar wipe clean tool.

Firefox programmer Ehsan Akhgar explained in a blog post yesterday why Mozilla has done a sudden U-turn by adding the porn mode to Firefox 3.1.

"Private browsing aims to help you make sure that your web browsing activities don't leave any trace on your own computer," he said.

Mozilla previously shied away from adopting a “porn mode” feature in its browser. But in September it responded to challenges from browser rivals Apple, Microsoft and Google by reviving private browsing features in Firefox. ®