TRENTON, N.J. (CBSNewYork) — A New Jersey lawmaker wants Congress to look into the relationship between fantasy sports websites and professional leagues.

Rep. Frank Pallone, D-N.J., ranking member of the Energy and Commerce Committee, has asked the panel to review the legal status of fantasy sports.

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Pallone wants to know how fantasy sports differ from traditional sports gambling, which is illegal except in states that legalized it before 1992.

The congressman noted that NFL fans were inundated by TV ads last weekend promoting fantasy sites during games. He added that leagues sponsor their own fantasy games and have sponsorship deals with other fantasy sports operators.

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New Jersey has been fighting in court to legalize sports betting there. The major pro sports leagues have opposed the state’s efforts, which Pallone calls hypocritical considering their support for fantasy sports.

“The bottom line is they’re just against sports betting because they can’t control it,” Pallone told WCBS 880’s Kelly Waldron.

Fantasy sports allow fans to select a virtual team of real-life players and accumulate points based on their performances. The popularity of the games has exploded over the past 15 years.

While many leagues are compromised of friends or co-workers who play for free or pay fees of varying amounts into a jackpot to be paid to winners, a new crop of daily fantasy sports sites such as DraftKings and FanDuel have popped up in recent years. Those sites allow paying participants to select a new team, or multiple teams, every day, and large cash prizes are awarded to the top peformers.

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According to Pallone, a loophole in the federal gambling ban exempts fantasy sports games if they meet certain criteria.