The French league said it has lodged a criminal complaint against unknown persons after monitors flagged unusually heavy international betting on Elye Wahi to receive a yellow card in Nice's 0-0 draw with Metz on May 17.
The LFP said the alerts pointed specifically to wagers on Wahi being cautioned, prompting it to notify police, gambling regulators and the French Football Federation over suspected sports corruption and organized fraud.
Wahi, 23, was booked in that final-round Ligue 1 match and his representatives did not immediately respond to requests for comment.
The case surfaces while Wahi is at the World Cup with Ivory Coast, which beat Ecuador 1-0 in its opener and next faces Germany on Saturday in Toronto.