Major League Baseball (MLB) has forbid its teams and their broadcast partners from accepting advertising from sports betting companies.

On Wednesday, New Jersey news outlet ROI-NJ reported on a June 8 memo that MLB’s deputy commissioner and chief legal officer Dan Halem sent to television and radio rights holders, reminding them that “they are presently not permitted to accept” advertising from sports betting operators.

Halem added that MLB clubs “may not at this time enter into any relationship with a pure sports book, or with a casino with a sports book to the extent that the arrangement involves sports betting.” Halem clarified that this week’s owners’ meeting would address how to develop “appropriate policies in this very complicated area.”

The memo appears to be in reaction to an advertising purchase by Dennis Drazin, head of the company that runs New Jersey racetrack Monmouth Park, which is scheduled to take the Garden State’s first legal sports wager at 10:30am on Thursday.