Lawmakers are calling for a probe into the tracking mechanisms known as “supercookies,” which are a more persistent type of the common cookie.

Reps. Ed Markey (D-Mass.) and Joe Barton (R-Tex.), co-chairmen of the bipartisan privacy caucus in the House, wrote to the Federal Trade Commission on Tuesday to ask the agency to look into the supercookies, saying that they invade user privacy.

Hulu.com and MSN.com were both identified as Web sites using the new kind of tracking method in research from Stanford University and the University of California at Berkeley, the Wall Street Journal reported. Supercookies, which are legal, can re-create a user’s profile information even after he or she has deleted traditional cookies, the report said. Companies also use a tracking method that compares user histories against a set of 1,500 Web sites to build user profiles. Many sites found to be using the method were seemingly unaware of the fact. MSN.com and Hulu both said that they have taken action to deal with the tracking.

Markey and Bardon said that they believe supercookie use could be in violation of the FTC’s rules regarding “unfair and deceptive acts of practices.

“I think supercookies should be outlawed because their existence eats away at consumer choice and privacy,” Barton said in a statement.