UEFA are "looking into" claims a banana was thrown on to the pitch during Italy's European Championship game against Croatia on Thursday.
A photographer was reported to have witnessed a steward retrieving a banana in the 1-1 Group C draw in Poznan as well as hearing monkey chants directed at Italy striker Mario Balotelli.
European football's governing body confirmed they were aware of the claims, telling Press Association Sport: "We are looking into the reports."
If the alleged banana-throwing incident was intended as an insult towards Balotelli, it would arguably represent the most serious bout of racism at a tournament that has been dogged by the problem.
Balotelli said before Euro 2012 that he would "kill" anyone who threw a banana at him in the street and would "not accept racism at all".
UEFA are already probing allegations of racist abuse against the Manchester City striker in Italy's opening match against Spain on Sunday.
On Monday, Italy boss Cesare Prandelli rejected claims Balotelli was abused against Spain, saying: "That's absolutely untrue."
Balotelli, 21, said he would walk off the pitch if he was racially abused by fans at Euro 2012. UEFA are also looking into allegations Czech Republic defender Theodor Gebre Selassie was subjected to monkey chants during his side's Group A opener against Russia last Friday.
Holland players claimed they heard racist chanting during an open training session in Krakow before the tournament even began.
Meanwhile, Balotelli could lose his place in Italy's starting line-up for Monday's final Group C game against Republic of Ireland. The striker has been substituted in both his country's games so far and Prandelli said on Friday: "He has huge potential, but he needs to improve. He needs to be more ruthless and pay more attention. These are the areas he needs to improve."