The NCAA bans DraftKings and daily fantasy sports provider FanDuel from their events. In a letter sent Tuesday, college sports’ largest governing body notified executives from DraftKings and FanDuel it would cancel future meetings and ban advertising from the two popular websites during NCAA championship events such as the men’s basketball tournament.

Because the NCAA believes the fantasy games meet the definition of wagering, it has decided to ban all advertising, on site and on television, during championship events – a potentially big hit for two companies that have become major advertisers, particularly on television. The NCAA said its advertising policy for broadcasters “has a longstanding section that states we will not accept advertising from sports wagering entities.”

The ban does not necessarily apply to the College Football Playoff, which is not run by the NCAA. While the CFP abides by NCAA bylaws, the organization has discretion over advertisements during its three games.

“What I can say is that we have not discussed it,” CFP executive director Bill Hancock told The Associated Press. “Whether we will or not remains to be seen. We’re watching the situation with great interest.”

The unregulated daily fantasy sports industry is under scrutiny from regulators and lawmakers after it unleashed an advertising campaign promising to make millionaires out of players competing on the sites. Customers pick player lineups and win based on points earned during a single day.

More about why the NCAA bans DraftKings and FanDuel at CDC Gaming Reports.