Mozilla and Google have extended their partnership for at least the next three years, negotiating a confidential deal that will result in a “significant and mutually beneficial revenue agreement.”

“Under this multi-year agreement, Google Search will continue to be the default search provider for hundreds of millions of Firefox users around the world,” said Gary Kovacs, CEO, Mozilla.

“Mozilla has been a valuable partner to Google over the years and we look forward to continuing this great partnership in the years to come,” said Alan Eustace, Senior Vice President of Search, Google.

Mozilla Firefox currently uses Google as the default search engine and the latter pays Mozilla each time someone uses its service via the popular web browser. The referral scheme has netted Mozilla millions of dollars in revenue.

In 2010, 98 percent of Mozilla’s $123 million revenue was apparently made through search engine referrals, including those via Bing, Yahoo and Amazon. However, 85 percent of the total revenue in 2012 is said to have been made through Google’s search engine.

This week Firefox released the latest version of its browser, which apparently improves stability and browsing speeds by up to 30 percent.