Millwall have insisted anyone found guilty of violent behaviour during the club's FA Cup semi-final defeat to Wigan at Wembley will be banned for life.
The Football Association and Metropolitan Police are investigating Saturday's events, and a statement on the club's official website read: "Millwall Football Club will do everything possible to assist the Football Association and the Metropolitan Police investigating the disorder that occurred during Saturday's FA Cup semi-final against Wigan Athletic at Wembley Stadium."
The club's CEO, Andy Ambler, added that any supporter found to be responsible for the trouble would be issued with a life ban.
"Our position is clear," he said. "Anyone associated with our club found guilty of violent behaviour will be banned indefinitely from Millwall matches in addition to any punishment they receive from the authorities.
"Having worked so hard to show the positive side of our club both on and off the field, we cannot allow the actions of a mindless minority to undermine that. At this stage we are still in the process of establishing the full details of what happened in a section of the ground during the second half.
"When we have those facts at our disposal and the police have completed their investigations we may be in a position to comment further."