According to L'Equipe, the 33-year-old centre-back was involved in a physical fight with Montpellier head coach Michel Der Zakarian on Tuesday evening.
The report claims that Montpellier players had to separate the two men during a training session, with Sakho allegedly grabbing the coach by the collar and making him fall to the dressing room floor.
Sakho reportedly stormed off the training pitch when Der Zakarian did not penalise a foul against him during a training match. The 60-year-old confronted the defender and told him that it was not his decision when to train or not. Sakho was said to be angered by that and complained about his lack of game time in Ligue 1 - having been restricted to just six minutes on the pitch this season.
L'Equipe also claim that Montpellier could terminate Sakho's contract - which is due to expire at the end of the season - if they find him guilty of serious misconduct.
Montpellier signed Sakho in July 2021, after the expiration of his contract at Crystal Palace. The Frenchman previously played in the Premier League at Liverpool, making 80 appearances for the club between 2013 and 2017.
Der Zakarian did not comment on the incident when approached by L'Equipe.