Sports-betting platform DraftKings Inc. has been using names and images of Major League Baseball players without permission and in violation of Pennsylvania law, their union alleged in a lawsuit.

Boston-based DraftKings and another popular betting site — Bet365 — are misappropriating pictures of hundreds of professional baseball players and using them in marketing campaigns, according to the suit filed Monday in federal court in Philadelphia. The city is home to the Phillies, which currently have more wins this season than any other MLB team.

"Defendants’ use of player images within their sportsbook platforms is not merely informational — it is promotional,” the union’s lawyers said in the complaint. "Users could bet that the Phillies will beat the Marlins, or that Bryce Harper will hit more than two home runs in a given game, without seeing Harper’s valuable image. Indeed, both DraftKings and Bet365 offer the same types of bets in other sports without using player images.”