The Football Association has urged England supporters to act in a "responsible and respectful way" after UEFA threatened severe action if the shameful scenes that marred the Euro 2016 opener against Russia in Marseille are repeated.
European football's governing body warned that both nations risk being expelled from the competition if scenes similar to the three days of fighting between English fans, their Russian counterparts and local gangs in the build up to Saturday's 1-1 draw at the Stade Velodrome happen again.
Moments after Vasili Berezutski had scored a last-minute equaliser for Russia, sections of their support stormed over a tarpaulin barrier towards English supporters, who fled over barriers.
Saturday night in Marseille saw more flashpoints, as riot police fired tear gas into squares, bars and restaurants as more fighting erupted and FA chief executive Martin Glenn said his organisation had no doubt over the seriousness of UEFA's words.
"We take this letter from UEFA with the utmost seriousness," he said in a statement.
"We understand the potential implications of our supporters' actions and wholly accept that every effort needs to be made by the FA to positively urge them to act in a responsible and respectful way.
"Violent scenes like those witnessed over the weekend in Marseille have no place in football, nor society as a whole.
"We want people - fans and locals - to feel safe and enjoy a festival atmosphere at the Euros and we will continue to work closely with all the relevant authorities to achieve that."
Speaking to ITV news, Glenn strongly criticised the behaviour of a section of England fans but acknowledged there were other factors at play.
"I really would not single out England fans, which is not to say there hasn't been behaviour that we would define as deplorable and embarrassing.
"I would reiterate to England fans the support inside the stadium was magnificent, we are talking about a minority of people involved in anti-social behaviour."
UEFA has opened disciplinary proceedings against the Russian Football Union in relation to the flashpoint following full-time, while Euro 2016 was marred by further fan violence on Sunday as Germany and Ukraine fans clashed ahead of their teams' meeting in the late kick-off in Lille.