UEFA vowed to tighten security and segregation at games in the wake of the violent scenes that marred the 1-1 draw between England and Russia in Marseille on Sunday (AEDT), promising sanctions for both nations, including disqualification from the tournament, should the misbehaviour flare up again.
In statement released overnight, the European governing body said:
"The UEFA Executive Committee would like to express its disgust for the violent clashes which occurred in the city of Marseille.
"Such unacceptable behaviour by so-called supporters of the national teams of England and Russia has no place in football, a sport we must protect and defend."
Both countries were threatened with expulsion from the tournament if the violence reoccurs.
"The UEFA Executive Committee has warned both football associations that – irrespective of any decisions taken by the independent disciplinary bodies relating to incidents inside the stadium – it will not hesitate to impose additional sanctions on the Football Association (FA) and the Russian Football Union (RFS), including the potential disqualification of their respective teams from the tournament, should such violence occur again.
"We urge both the FA and the RFS to appeal to their supporters to behave in a responsible and respectful manner.
"We would also like to publicly voice our support for the work of the French authorities and security forces for their efforts to deliver a safe and secure tournament in challenging circumstances."