Google's Chrome's growing popularity appears to be eroding support for Microsoft Internet Explorer and Mozilla Firefox.

In January, according to NetApplications, Google Chrome's global market share reached 5.2%, a gain of 0.57 percentage points from the previous month.

Microsoft Internet Explorer saw its global market share drop to 62.18%, a decline of 0.51 percentage points in January. Mozilla Firefox slipped to 24.41%, a decline of 0.2 percentage points.

Apple's Safari browser gained 0.05 percentage points to reach 4.51% market share in January, having fallen behind Chrome for the first time last month.

Opera's global market share declined from 2.40% to 2.38% during this period.

Chrome's gains in part reflect the power of advertising on the Google Search page. Google continues to run an ad on its Search page urging users of Internet Explorer to try Chrome. Firefox users are not presented with Chrome ads.

Chrome may also be benefiting from advisories, issued last month by government IT security organizations in France, Germany, and Australia, to use a browser other than Internet Explorer. The recommendations were prompted by reports that December's cyber attack from China on Google and other companies tried to exploit an Internet Explorer vulnerability.

For Mozilla, which lost market share in December as well as last month, at least by NetApplications' measure, the trend isn't a good sign. The company recently reported that Firefox usage grew by 40% overall in 2009 and that it gained users in France, Germany, and Australia following the Internet Explorer advisories issued in those countries.

A spokesperson for Mozilla was not immediately available for comment.

Internet Explorer's decline coincides with an effort by Google and others to encourage users of legacy browsers like Internet Explorer 6 to start using a browser than supports HTML5 and other modern Web technologies.

On Friday, Google said that next month, it plans to stop supporting Internet Explorer 6 on Google Docs and Google Sites.

Microsoft isn't about to give up, however. It has been encouraging users to upgrade to Internet Explorer 8 and appears to be committed to making Internet Explorer 9 more competitive with other modern browsers in terms of JavaScript performance. That won't necessarily resolve other compatibility differences however.