Auxerre president Gerard Bourgoin called for an investigation on Saturday after his player Kamel Chafni claimed he had been racially abused by an assistant referee.
Chafni, a Morocco international, was sent off following an altercation with the official, Johann Perruax, in the 55th minute of Auxerre's 1-0 loss at Brest in the French top flight.
The midfielder had to be restrained by his team-mates, as well as players from Brest, and as he left the pitch, following a delay of five minutes, he told television cameras he had been the victim of racist abuse.
"There was a serious incident and the player has sworn on his honour," Bourgoin told reporters afterwards.
"It appears that the official told him: 'Sod off, Arab.' If that's the case, it's very serious.
"I didn't hear it personally, which is why I'm going to ask the league to open an inquiry. If we're not successful, the boy will make a formal complaint."
Bourgoin also claimed that players from Brest had verified Chafni's version of events.