Europe is a fortress for Mozilla's Firefox browser, which now enjoys a market share nearly 50 percent higher than in the US, a French Web-measuring company has reported.

According to July data from XiTiMonitor, Firefox accounted for 27.8 percent of browsers used in Europe, an increase of 3.6 percentage points from the March measurement.

XiTiMonitor's survey of almost 96,000 sites in 32 European countries - from Ireland to Ukraine, Finland to Greece - also said Microsoft's Internet Explorer held a 66.5 percent market share, with Opera, Safari and Netscape rounding out the top five with 3.5 percent, 1.7 percent and 0.3 percent, respectively.

Slovenia, Finland and Slovakia had the greatest Firefox penetration, with the open-source browser accounting for 47.9 percent, 45.4 percent and 40.4 percent, respectively, during a week-long stretch from July 2 to July 8. Other Firefox strongholds include Germany (38 percent), Poland (39.6 percent) and Ireland (38.6 percent).

By XiTiMonitor's tally, Firefox's North American market share was pegged at 18.7 percent, higher even than the worldwide number set by US-based metric vendors. Net Applications, for instance, put Firefox's June global market share at 14.55 percent, which was off more than half a percentage point from March. XiTiMonitor, meanwhile, claimed that Firefox's share had climbed in every region.

SpreadFirefox, Mozilla's community marketing program, wasted no time in posting XiTiMonitor's numbers.