Firefox lets users track who is spying on them

Mozilla, the maker of Firefox, has unveiled a new add-on for the popular web browser that gives users an instant view of which companies are "watching" them as they browse.

Mozilla, the maker of Firefox, has unveiled a new add-on for the popular web browser that gives users an instant view of which companies are 'watching' them as they browse, the Daily Mail reported on Friday.

The move comes the same week that Google pushed ahead with its controversial new privacy policy, built to provide even more data for Google's $28 billion advertising business - despite concerns that the harvesting of private data might be illegal in many countries.

The Collusion add-on will allow users to 'pull back the curtain' on web advertising firms and other third parties that track people's online movements, says Mozilla CEO Gary Kovacs.

Google's business is built on advertising - the company earned $28 billion from its AdWords service in 2010.

Google's new privacy policy allows it to 'streamline' data from Android phones, YouTube, Gmail and web browsing to target its adverts even more precisely towards individual web users.

Mozilla's Firefox is the world's second most popular web browser, a position under threat from Google's own Chrome browser. The Collusion add-on is an official Mozilla product, and was unveiled at the Technology, Entertainment and Design conference this week by Mozilla CEO Gary Kovacs.