SEATTLE (Reuters) - Google Inc's <GOOG.O> Chrome Web browser has grabbed more than 20 percent of global market share, while Microsoft Corp's <MSFT.O> long-time leader Internet Explorer has slipped below 50 percent, according to Internet statistics firm StatCounter.
A sevenfold increase in usage in the last two years is a boost for Google, which is trying to convert its dominance in Web search into operating systems and mobile software, bringing it into direct competition with Microsoft.
Google's Chrome browser, launched in December 2008, took 20.7 percent of the global market in June, according to StatCounter, up from 2.8 percent in the same month in 2009.
In the same time, it said the various versions of Internet Explorer fell to 44 percent from a 59 percent share two years ago, while Mozilla's Firefox dipped slightly to 28 percent from 30 percent.
Google's gains come as the company makes a concerted push into browser-centric, or "cloud" computing. In May, Google launched its long-awaited Chromebook, a laptop that works almost entirely on software accessed via the Internet, rather than installed on the machine. This is a direct challenge to software leaders Microsoft and Apple.
Microsoft, which controlled as much as 95 percent of the market in the early 2000s after crushing browser pioneer Netscape, has seen its market share ebb after disputes with antitrust regulators in the United States and Europe, which accused Microsoft of abusing its monopoly in operating systems to dominate the browser market.
The resolutions of those disputes effectively prohibited the world's biggest software company from making Internet Explorer the default browser in its dominant Windows operating system. Microsoft, which is developing the IE10 version of its browser, settled the issue with European Union regulators in December 2009, pledging to give consumers better access to rival browsers.
StatCounter, based in Dublin, Ireland, says its statistics are based on data collected from a sample of more than 15 billion page views per month from more than 3 million websites.
Net Applications, a more widely used browser statistics source, estimates that Google has not increased its share quite as much.
According to its market share data for June, Microsoft's Internet Explorer leads with 53.7 percent, Firefox has 21.7 percent and Chrome 13.1 percent. Apple Inc's Safari has 7.5 percent and Norway's Opera Software <OPERA.OL> 1.7 percent.
(This story was corrected to show comparison period two years ago, not one)
(Reporting by Bill Rigby. Editing by Robert MacMillan and Gerald E. McCormick)