In February, Yahoo launched a search toolbar for Firefox but users of the open source browser were forced to revert back to IE to access some Yahoo features. For example, Yahoo Messenger users still cannot use Firefox to customise their online avatar and have to revert back to IE.

However, a Yahoo spokesperson told ZDNet Australia  on Tuesday that the company would not launch any new products or services in the future without ensuring that they work on both IE and Firefox.

"Due to the explosive popularity of the Firefox browser, it has now been added to our suite of browsers to test our products against. All new products that Yahoo develops will be tested against Firefox," the spokesperson said.

However, Yahoo would not commit to a date when all its current services – including avatar customisation – will be available to Firefox users.

"We understand that consumer usage of Firefox has steadily increased and we are committed to providing an enhanced consumer experience. While we are unable to provide you with an exact date, I can tell you we are actively working to provide Firefox support for avatars," the spokesperson said.

Yahoo's decision to only launch new products that support both major browsers is huge boost for Firefox, according to Foad Fadaghi, senior industry analyst at Frost & Sullivan Australia.

"The momentum right now is behind Firefox. The Internet players are making sure they don’t miss out if there is a mass migration--they have realised that it is not just a Microsoft game anymore," said Fadaghi.

Fadaghi said that another likely reason why Yahoo has committed to Firefox is because the open source browser has such close ties with Google.

When Firefox 1.0 was launched late last year, its default home page featured a Google seach box.

"There is already a lot of support from Google, so as far as Yahoo is concerned they are 'keeping up with the Joneses'. It is a bit of a land grab," said Fadaghi.