A sports betting law in Delaware is in violation of a federal prohibition against sports gambling, a federal appeals court ruled Monday.

The Delaware legislation had been challenged by the NFL, NBA, NHL, Major League Baseball and the NCAA in a lawsuit.

Delaware was exempted from the federal ban on sports gambling. But the professional leagues and the NCAA had maintained that the Delaware legislation is illegal because the state was planning to offer single-game betting for the first time.

A three-judge panel in Philadelphia made the ruling after hearing arguments from attorneys for both sides for nearly two hours Monday, the Associated Press reported.

Delaware had intended to put its sports betting plan into effect next month as a revenue-generating mechanism.

Now state officials must decide whether to accept parlay bets on multiple NFL games, which the leagues did not contend is illegal. State leaders also must decide whether to appeal Monday's ruling, either to the full appeals court or to the U.S. Supreme Court.

"We're very disappointed with today's ruling," Michael Barlow, the legal counsel to Gov. Jack Markell, said, according to the AP.