UEFA president Michel Platini hinted on Tuesday that European football's governing body would come down hard on Serbia if claims that several England under-21 players were subjected to racist abuse there are proven.
"We'll collate all the reports, we have the television pictures, the disciplinary committee is already on it," Platini said on the sidelines of a Euro 2016 organising committee meeting here.
"But we have already dished out a yellow card to Serbia (for previous instances of trouble).
"Racism is a problem that affects us massively. We're fighting it, and that's what I replied to the British prime minister, who wrote to me."
England Under-21s' 1-0 victory over Serbia in Krusevac last week, which saw them qualify for next year's European Championship in Israel, was overshadowed by apparent racism from the stands towards England full-back Danny Rose.
The Serbian federation (FSS) issued a statement "absolutely" denying there was any racism at all and branding the England players' behaviour "vulgar".
UEFA charged both the English and Serbian associations for the improper conduct of their players, and the Serbs for "alleged racist chanting" by fans.
Britain's Prime Minister David Cameron was said to have been "appalled" at the scenes from the match in Krusevac.
Cameron wanted "tough sanctions" against Serbian football if racism is proven, according to a spokesman.
The UEFA disciplinary committee will meet on November 22 to decide what, if any, punishment needs to be meted out.