Several lawmakers and consumer advocacy groups in the US have urged the Federal Trade Commission to look into Facebook tracking its users’ activities online even after they log out of the network.

Representatives; Edward J. Markey (Democrat-Massachusetts) and Joe Barton (Republican-Texas) have written a letter to the FTC saying the social network’s use of “cookie” software should be investigated under the “unfair and deceptive acts” clause of the agency’s mandate.

The move follows an incident in which an Australian blogger, Nik Cubrilovic had raised alarm claiming he found that Facebook continued to deliver ‘cookies’ to his web browser that could be used to track users who have logged out of the platform.

Mr Cubrilovic was at the centre of the latest controversy over privacy on Facebook after he posted a blog on Sunday. The blog showed that Facebook was still collecting identifiable information about users after they had logged out through cookies. These cookies are small text files that can collect information about a user’s browsing. This information, which includes Facebook user ID, can then be transmitted to servers for analysis.

“When people log out of Facebook, they are under the expectation that Facebook is no longer monitoring their activities. We believe this impression should be the reality,” wrote Markey and Barton , who chair the bipartisan Congressional Privacy Caucus.

The Electronic Privacy Information Center and nine other consumer and privacy groups also made similar requests on Thursday.