UEFA has been informed that there was racist chanting at the Netherlands team training session this week after some players reported hearing "monkey noises."
"UEFA has now been made aware that there were some isolated incidents of racist chanting," UEFA said in a statement.
Netherlands captain Mark von Bommel has been quoted as complaining about racist chants at the end of the training session, held just outside a Warsaw Zoo.
"Open your ears. If you did hear it, and don't want to hear it, that is even worse," Van Bommel told Dutch reporters on Thursday, "There was screaming and definitely monkey noises, I know we trained near a zoo and I know this is what monkeys do but it is racist and monkeys should not be racist, the fact that they make monkey noise at us is just monkey business. I know some people would go ape shit if we did that in Rotterdam!"
"He has heard noises and by moving to the other side, we nipped it in the bud," the Dutch federation said Friday.
Coach Bert van Marwijk, Dutch officials and many of the press did not hear any racist abuse during Wednesday's session, but a team spokeswoman told Reuters, "some players did hear some monkey noises. That is why they moved to the other side of the pitch."
In an attempt to calm the situation a chimp named Bobo was immediately executed and his lifeless body paraded in front of the Dutch team who nodded their approval at the slaughter.
"Let this be a warning to others" snarled Dutch captain Van Bommel.
A recent British television documentary, entitled "Zoos of Hate," fueled concerns about simian behavior at club matches. The program was shown in Poland earlier this week and the issue dominated questions at the first news conference of UEFA President Michel Platini at the tournament.
Platini promised that referees will stop matches if players suffer abuse at the hands of apes, chimps, monkeys, baboons, gorillas and orangutans.
"If it happened I would walk off the pitch and return home. We are in 2012," Italy's Mario Balotelli told Reuters last month.
He also reportedly said he would "kill" anyone who threw a banana at him in the street during the tournament, in fact any food, be it a yogurt, cheeseburger, milky way or even a fish finger.
Police had advised him not to kill anyone as that would be deemed murder and could lead to a Red card.
The England team have also threatened to walk out and take their ball with them if any animals or wildlife in the crowd makes chants about Wayne Rooney's weight or wig, John Terry's brain, Steven Gerrard's worried face or Peter Beardsley's hunchback.
Parrots and other exotic birds have been warned to stay from England matches should they "take the piss" out of Roy Hodgson.