Six Nations officials are looking into claims of racist abuse aimed towards Wales prop Samson Lee in Saturday's 25-21 defeat to England in the Six Nations.
A video has emerged online in which Lee appears to be called "gypsy boy" during the first half at Twickenham.
Audio from the microphone of referee Craig Joubert picked up the apparent abuse.
The incident happened during a melee between the two teams, which led to Lee and England front row Joe Marler squaring up.
A Six Nations spokesperson subsequently told Omnisport that the tournament's officials are in the process of establishing the facts of the episode.