Mozilla, the maker of of Firefox, today announced that it has struck a new three-year deal with Google in which Google will remain the default search engine in the browser.

The financial terms were not disclosed, but reaching a new deal with Google has been seen as critical for Mozilla, a Silicon Valley nonprofit software maker.

Mozilla, which is charged with defending openness on the Web, recently reported that Google provided the lion's share of Mozilla's $120 million in revenues in 2010. That was an 18 percent jump in revenue from 2009.

The last agreement between Mozilla and Google, in place since 2008, technically expired in November.

Firefox, once dubbed "Googlefox" because of Google's support, now has competition in Chrome, Google's own browser. But the overall objective of Chrome is to speed up the Web and improve it as a foundation for applications, not to squeeze other browsers off the Internet.

And Mozilla has been hedging its bet. Earlier this year, it introduced Microsoft's Bing as a search-engine option with Firefox 4, and in October, it released a version of Firefox with Bing as the default search engine.