The National Football League is holding the Super Bowl in the gambling capital of the U.S. for the first time, but Commissioner Roger Goodell is reminding team personnel they are not allowed to take part in the action.

Goodell sent out a memo Thursday ahead of Super Bowl 58 in Las Vegas, telling staff from all teams that the league’s policy bars them from betting on sports or entering a sportsbook in Vegas. Employees of the participating Kansas City Chiefs and San Francisco 49ers will not be allowed to play even casino games until Super Bowl LVIII concludes on Feb. 11.

“Super Bowl LVIII is a highly anticipated and thrilling event for our fans and viewers. With fans across the globe tuning into the game and related events, we must all do our part to protect the integrity [of] our game and avoid even the appearance of improper conduct,” Goodell said in the memo that was obtained by CNBC.

The league issued the guidance as professional sports navigate the new world of legalized sports gambling. Gambling is now legal in 38 states, and more than $300 billion has been wagered since a law restricting the practice was repealed in 2018, according to the American Gaming Association.

Super Bowl 58 in Vegas is expected to be the most bet on NFL championship ever. While professional sports leagues once frowned upon betting, they have now embraced it as a burgeoning revenue stream.

GeoComply, which tracks sports betting by location, says it has seen a 24% increase in gambling transactions since the start of the NFL playoffs, compared to the same period last year.

The NFL’s memo contains a list of rules that apply to owners, executives, coaches, football and medical personnel and office staff on all teams. Separate, tougher restrictions apply to players. They are subject to one- or two-year or even indefinite suspensions, if caught gambling on their team or other games, according to the league’s adjusted gambling policy announced in September.

Nearly a dozen players have received suspensions for violating the league’s rules. The NFL is currently investigating 2023 sixth-round draft pick Kayshon Boutte, who allegedly place 8,900 bets over 13 months while under the legal gambling age when he was at Louisiana State University.

The league memo sent Thursday reminds personnel that they should never bet on the NFL or any other sport.

Staff must also strictly avoid sportsbooks, even for food or drink, while at the Super Bowl. To help prevent employees from entering the facilities, the league has teams staying in hotels about 30 minutes away from the Las Vegas strip.

Rules are slightly looser for casino, card and table games, along with slots.

Nonparticipating team personnel in Vegas are permitted to play casino games or slots during their personal time or off hours. However, employees of the Chiefs and 49ers won’t be allowed to play until the Super Bowl is over.

NFL office staff is banned from gambling of any kind at any time, according to the memo.

The league also reminded personnel to never share game, team or player “inside information,” and to report any requests for that data.

Correction: This story has been updated to reflect NFL gambling suspensions start at one to two years for players.

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