Following his findings that Facebook are able to track users after they log out of the social network, Australian technology blogger Nik Cubrilovic, in cooperation with 10 public interest groups, has sued the firm, paving the way for a legal definition of user privacy and parameter sets for Facebook's next moves.

The group's suit, filed on Friday before the US Federal Trade Commission, is based heavily on Facebook's tracking of the social network user's data even after the user has logged out. The group calls this act a means of tracking and an invasion of privacy.

The 10 public interest groups also urged the commission to look into Facebook's new ticker and timeline features and decide whether these items increased privacy risks for users, considering the features make biographical and important information of users easily accessible by 'friends of friends.'

Cubrilovic has earlier complained that Facebook does not delete tracking ''cookies'' but only modifies them, and in the process keeping information that can identify users as they surf the internet.

The company has told users cookie files installed on their computers to track interactions with Facebook applications and websites are removed when they log off, according to a complaint in the US Federal Court in San Jose, California.

Facebook admitted last week that the cookies track internet activity after users log off, according to the suit.

''This admission came only after an Australian technology blogger exposed Facebook's practice of monitoring members who have logged out, although he brought the problems to the defendant's attention a year ago,'' the complaint states.

The lawsuit - filed by Perrin Aikens Davis, of Illinois - seeks class status on behalf of other Facebook users in the US.

Davis seeks unspecified damages and a court order blocking the tracking based on violations of federal laws, including restrictions on wiretapping, as well as computer fraud and abuse statutes.

''We believe this complaint is without merit and we will fight it vigorously,'' Andrew Noyes, a Facebook spokesman, said in a statement.

The Committee's decision will influence Facebook's next moves and send a statement to social network users on how much information they could upload to Facebook and other social network sites.