Two members of Congress have asked the U.S. Federal Trade Commission to investigate Facebook tracking practices.

U.S. Reps. Edward J. Markey (D-Mass.) and Joe Barton (R-Texas) made the request after the news broke that Facebook was collecting “information about the websites its users visited even after users logged out of Facebook,” the Congressmen said a press release.

The Congressmen wrote a letter which asks FTC Chairman Jon Leibowitz to investigate the practice, adding that “Facebook tracking its users even after they log out should fall within the FTC’s mandate with respect to protecting Americans from ‘unfair and deceptive acts or practices.’”

“We believe that tracking users without their knowledge or consent raises serious privacy concerns,” the two members of Congress said in a joint statement. “When users log out of Facebook, they are under the impression that Facebook is no longer monitoring their activities. We believe this impression should be the reality.”

The news comes as Mobiledia reported that Nik Cubrilovic, an Australian blogger, learned about the tracking issue in 2010 but did not “get an official response until he wrote about it on a blog post over the weekend.”

Cubrilovic says Facebook got information after users logged out and visited websites with Facebook's "Like" buttons, Mobiledia said. Some 900,000 sites have the feature, Mobiledia added.

Facebook said it “did not store or use any information that it should not have,” Mobiledia said.

"There was no security or privacy breach," Andrew Noyes, manager of public policy communications at Facebook, told Mobiledia via e-mail.

Markey and Barton are co-chairs of the Bi-Partisan Privacy Caucus, and have been interested in the issue previously.

Markey and Barton wrote to Facebook in October 2010 after The Wall Street Journal reported how privacy breaches affected “tens of millions” of Facebook users when personal information was leaked to third party applications, according to the congressmen.

In May 2011, Markey and Barton said they wrote to Facebook about how Facebook “provided advertisers, analytics firms and other third parties the capability to access Facebook users’ accounts and personal information.”

Also, in February 2011, the two wrote to Facebook “with questions about the company’s proposed plan to make users’ addresses and mobile phone numbers available to third-party websites and application developers.”

Markey and Barton have introduced a “Do Not Track Kids Act of 2011” about the collection, use and protection of personal information from children and teenagers.

The issues generated by the tracking practices have led to one analyst writing on TechZone360 to say that “it now appears that the only way people can have real privacy when it comes to Facebook is to either completely delete every Facebook cookie on your browser after each visit, or use an entirely different browser than you normally do when Facebooking. Both of those options count as a real pain.”