New York, Sept. 2: The browser war is back on. This time, Microsoft’s opponent is Google, a familiar foe.

Google will release a free Web browser called Chrome that the company said would challenge Microsoft’s Internet Explorer, as well as the Firefox browser.

The browser is a universal doorway to the Internet, and the use of Internet software and services is rapidly growing. Increasingly, the browser is also the doorway to the Web on mobile phones and other mobile devices, widening the utility of the Web and Web advertising. Google, analysts say, cannot let Microsoft’s dominant share of the browser market go without a direct challenge.

Google already competes with Microsoft in online search and Internet advertising. They both make operating software for mobile phones. Google is increasingly competing with Microsoft head-on in software that handles basic productivity like word processing, spreadsheet, presentation and email programmes. Google has Web-based software in these markets that are low-cost or free alternatives to Microsoft’s lucrative desktop software. Despite the frequent clashes with Microsoft — including the role Google played in thwarting an attempted acquisition of Yahoo — Google has come out on top only in search and search advertising.

But Google does not have to win the browser war. Strategically, opening yet another front against Microsoft forces it to divert resources to defend franchises. Now, Chrome heightens the rivalry and marks a shift for Google, which has strongly backed Firefox, the open-source browser that has gained about a fifth of the market against the dominant Internet Explorer.

Google’s browser project has been under way for more than a year. In a brief statement, Microsoft welcomed the new entry and expressed confidence that people would prefer Explorer, which is on every Windows PC sold.