Warsaw, Poland (CNN) -- European football's governing body opened disciplinary proceedings Saturday against Croatia over what it said was racist behavior by its supporters during a Euro 2012 match against Italy.
UEFA said it was acting over "the setting-off and throwing of fireworks, and the improper conduct of supporters," including racist chants and the displaying of racist symbols.
The UEFA Control and Disciplinary Body will deal with the case on Tuesday, it said.
Croatia drew 1-1 in the match against Italy in Poznan on Thursday, with Mario Mandzukic scoring for the Croatians and Andrea Pirlo claiming a goal for Italy.
UEFA president Michel Platini urged fans who are attending decisive matches on Saturday night to "conduct themselves with dignity and respect."
Russia plays Greece in Warsaw, while the Czech Republic plays Poland in Wroclaw.
"Of course, there is rivalry and passion, and all teams want to win -- but we must remember that the results on the pitch are what really matter," Platini said in a statement.
"EURO 2012 is a celebration of football and I invite the fans, the vast majority of whom have conducted themselves in an exemplary manner so far, to continue to do so for the remainder of the tournament."
The issue of racism has threatened to mar the soccer tournament, which is being co-hosted by Poland and Ukraine.
Members of the Dutch squad claimed to hear monkey noises during an open training session in Krakow, Poland, before the tournament started, though the Dutch FA opted not to lodge an official complaint with UEFA.
In addition, family members of two black English players chose not to travel to the competition for fear of being subjected to racism.
UEFA has already taken the step of writing a letter to the mayors of each host city asking for a zero-tolerance approach to racist abuse.
UEFA's disciplinary body has also been busy since the tournament started just over a week ago.
Russia has already been fined and handed a suspended points deduction for improper conduct against the Czech Republic, while also still awaiting the verdict of a UEFA investigation into alleged racist chanting during the match.
The German Football Federation was fined $12,500 after its fans threw paper onto the pitch during a meeting with Portugal, with the Iberian team also ordered to pay $6,250 for delaying the start of the second half.
A Danish player, Nicklas Bendtner, may also face sanctions next week after lowering his shorts during a game Wednesday to reveal that he was wearing underwear displaying the name of an Irish bookmaker named Paddy Power.
Under the laws of the games as outlined by FIFA, the global body which governs soccer, undershorts must be the same color as the shorts worn by the player. His shorts were red but the Paddy Power undershirts were green.
CNN's Claudia Dominguez and Tom McGowan contributed to this report.