Ten public-interest groups have asked the US Federal Trade Commission to investigate Facebook\'s tracking of internet users after they log off the world\'s most popular social-networking service. The Electronic Privacy Information Centre and nine other groups, in a letter filed with the FTC, also asked it to examine whether Facebook\'s new Ticker and Timeline features boost privacy risks for users by combining biographical information in an easily accessible format. \"We would like the FTC to investigate the extent to which Facebook\'s recent changes and its secret tracking of users after they have logged out constitute unfair or deceptive business practice,\" said David Jacobs, consumer protection fellow for Epic. Facebook, based in Palo Alto, California, is adding features to entice users to spend more time on the site and avoid losing them to Apple and Google, which also offer video and music services. Last month, Facebook chief executive officer Mark Zuckerberg unveiled new ways for members to use the social network to share music, movies, television shows, news and activities such as cooking and exercising. Blog posting The letter to the FTC references a September 25 blog posting by Australian blogger Nik Cubrilovic, who wrote that Facebook placed so-called ‘cookies\' on users\' browsers that tracked their internet activity even after they logged out of Facebook. Although Facebook moved to resolve the issue, \"it\'s unclear how complete the fix is,\" Jacobs said. \"There was no security or privacy breach,\" Andrew Noyes, a Facebook spokesman, said. \"Facebook did not store or use any information it should not have.\" Claudia Bourne Farrell, a FTC spokeswoman, confirmed that the agency received the letter. She declined to comment further. Facebook has ‘no interest in tracking people,\' engineer Gregg Stefancik said in a recent blog post. \"We do not share or sell the information we see when you visit a website with a Facebook social plug-in to third parties and we do not use it to deliver ads to you.\" The letter to the FTC is also signed by public interest groups the American Civil Liberties Union, the American Library Association, the Bill of Rights Defence Committee, the Centre for Digital Democracy, the Centre for Media and Democracy, Consumer Action, Consumer Watchdog, PrivacyActivism and Privacy Times. \"Facebook has been tracking the internet activity of users even after they have logged out of Facebook,\" the consumer groups state in the letter. \"Facebook has been engaging in post-log-out tracking for at least a year, and only issued a partial fix after facing intense criticism, indicating an unwillingness to respect consumer privacy without external pressure.\" Complete control Noyes said people who try the new features announced by Facebook will ‘find that they have complete control over whether their information is shared and with whom.\' \"We\'ve invested heavily, including consulting several privacy organisations, to build an authorisation dialogue that is obvious, easy to understand, and has a privacy setting built in,\" Noyes said. Epic previously urged the FTC to investigate Facebook\'s privacy practices, including default privacy settings and its facial-recognition feature. \"Facebook is misleading its users and also policymakers,\" Jeffrey Chester, executive director of the Center for Digital Democracy, who helped to write the letter, said in an email. \"The new changes are designed to pump big ad dollars into Facebook just prior to its IPO.\"