He said one Pole was injured in the fight and that three Croats were arrested and would most likely be released on Tuesday.
According to unofficial reports, Croatia's Bad Blue Boys and the supporters of Lech Poznan were involved in the fight. They were involved in a similar incident in Poznan ahead of the Croatia-Ireland game last week.
UEFA is keeping an eye on Croatian supporters because of a series of incidents caused by a small group of hooligans, the worst of which included racist slurs against black Italian footballer Mario Balotelli for which the Croatian Football Federation will be fined.