The French Judo Federation has warned judoka that they will be banned from the sport if they are caught teaching mixed martial arts (MMA).
The governing body is trying to keep hold of their judo stars following the case involving American Ronda Rousey, who won bronze at the 2008 Beijing Olympics, but now is involved in MMA.
President of the FJF Jean-Luc Rouge told L'Equipe: "Anyone [in judo] caught teaching MMA, will be removed from the French Judo Federation. MMA is illegal in France.
"All those who teach do not have the right and are liable to be written off. They put the Federation in trouble and if there is serious injury, it will be my fault."
The FJF currently has more than 500,000 members.