Toulon have released a statement confirming that England international Steffon Armitage and teammate Xavier Chiocci were held in custody on suspicion of assault.
Chiocci was released on Wednesday night, although Armitage remains in custody at this stage and a decision will be made regarding his release later today.
It is alleged that the pair were summoned by police following an attack on a 30-year-old male during a party earlier this week.
Both players are said to have no memory of the incident.
A statement from Toulon revealed that the club were "awaiting the results of the investigation and will, if necessary, place sanctions on the players to preserve the values that are dear to Toulon".
Armitage was last year crowned as the ERC European Player of the Year.