Increasing use of Firefox throughout Europe suggests that the browser battles aren't quite over, but may be headed for a slow-moving tug-of-war, according to a recent survey and analysts.

XiTi Monitor, a Web analytics company based in France, reported that use rate of the open-source browser among Europeans increased from 19.4 percent in April 2006 to 24.1 percent in March 2007.

The company draws its data from visitors to Web sites using its analytics service, which collects data such as the visitor's browser and location, said Anne-Laure Benzimera, communications manager for XiTi Monitor. The company's clients include MasterCard International Inc., the jeweller Cartier and McDonald's Corp., she said.

XiTi Monitor's numbers are on the high side in favor of Firefox for Europe, but coincide with other industry figures indicating gains for Firefox, said Gary Barnett, a research director at Ovum PLC. Those percentages of use can vary from 10 percent to 25 percent, he said.

XiTi Monitor's average for Firefox use worldwide is about 16.8 percent. That figure comes close to data from Net Applications, a company that also tracks browser market share.

For March, Net Applications reported Firefox had 15.1 percent of the market, up from 14.2 percent in February and 13.7 percent in January.

Microsoft Corp.'s Internet Explorer (IE) browser was firmly on top, holding 78.5 percent of the market. Like XiTi Monitor, Net Applications uses data from its analytics service.

Barnett said Firefox's gains could level off as early adopters and those most inclined to use it -- such as heavy Internet users and those familiar with the concept of open-source software -- simply run out.

"Then, the really hard work begins," Barnett said.

Home users tend to be ahead of businesses, too. While there may be some preferential use of Firefox, many enterprises still are using browser-based applications that are written to use some particular feature of Microsoft's IE.

But even though tabbed browsing, considered to be a major innovation, was adopted in Microsoft's IE7, Firefox still holds a major advantage with its add-ons -- free programs that add special functionality to the browser, Barnett said.

Those add-ons also allow Firefox to take advantage of newly favored Web 2.0 programming techniques, said Laurent Lachal, open-source director at Ovum.

Firefox is unlikely to make any more significant gains in market share without a deal from an original equipment manufacturer such as Dell Inc. to ship the browser on its hardware, said Colin Teubner, an analyst at Forrester Research Inc.

Most consumers find IE 7 adequate for their needs and are too lazy to change, he said.

"The impetus to switch is not as high," Teubner said.

XiTi found a very high use of Firefox in Slovenia, at 44.5 percent, and Finland, at 41.3 percent. Croatia, Germany and Slovakia exceeded 35 percent, according to XiTi.

One reason for those high rates may be the influence of Germany, where open-source software has a strong footing, Lachal said.

Firefox's lowest numbers came from Andorra, at 13.2 percent, followed by the Netherlands, 13.3 percent; Denmark, 13.8 percent; and Italy, 15.5 percent, XiTi said.