Firefox, the free, open-source browser from Mozilla, quietly gained enough users in March to finally grab 10 percent of the web browser market, according to a report released by web audience measurement firm Net Applications.

Firefox was used by 10.05 per cent of web surfers last month, up from 9.75 percent in February. That compared with the 84.7 percent of users on various versions of Microsoft's Internet Explorer (IE) in March.

Apple's Safari browser took third place with 3.19 percent of the market.

In the past year, Firefox has gained 3.34 percent share while introducing version 1.5 of the browser, which has an expanded range of features. Internet Explorer has lost 3.89 percent as users wait for IE 7.0, due out this autumn. The new version of IE will boast improved functionality and security.

"With a strong feature set, an aggressive product development cycle and an open-source platform, and by offering the browser for free, Firefox has the strategy in place to maintain its growth," Vincent Vizzaccaro, an analyst with Net Applications, wrote in the report. But Microsoft "has the much easier task of defending an entrenched position rather than attacking one", he added.

Netscape was the fourth most popular web browser, with 1.05 percent of the market, followed by Opera with 0.54 percent and Mozilla with 0.34 percent.