Mozilla To Trial Adverts Inside Firefox Browser
Mozilla says it plans to introduce adverts on the pages that appear when a user opens a new tab.
Currently a series of most-clicked sites are displayed when a user opens a tab, but the firm behind the browser says that could change.
In a blog post called 'New Tab Experiments', Firefox vice president said fresh instals of the browser could come with "a mix of our own sites and other useful sites" promoted.
He added: "Sponsorship would be the next stage once we are confident that we can deliver user value."
He attempted to reassure users that Firefox would not turn into "a mess of logos sold to the highest bidder; without user control, without user benefit".
He said: "That's not going to happen. That's not who we are at Mozilla."
The move is significant, given that most browsers have little to no overt advertising.
The latest version of Microsoft's Internet Explorer, for example, has a small text promotion for the firm's Bing services.
Meanwhile Google Chrome does not contain advertising but does use the company's lucrative search engine by default.
Non-profit Mozilla makes most of its money through a deal with Google to use its search engine by default.