Europe association football UEFA has confirmed there were some "isolated incidents of racist chanting" aimed at Netherlands players during an open training session for Euro 2012 - which starts today June 8 in Warsaw, Ukraine with the openning game between Poland and Russia. But the governing body has not revealed whether it is investigating the incident in Krakow, Poland.

Dutch captain Mark van Bommel said monkey chants were directed at players. "Should such behaviour happen at further training sessions, Uefa would evaluate the operational measures to be taken to protect players," Uefa said.

"Uefa has now been made aware that there were some isolated incidents of racist chanting that occurred at the open training session of the Dutch team yesterday in Krakow. Uefa has a zero tolerance policy when it comes to discriminatory behaviour and has given the power to referees to stop matches in case of any repeated racist behaviour."

The Dutch FA said in a statement that it would not be making an official complaint but was "more than willing to answer [the] questions of Uefa in this respect".

Outlining the incident, the statement added: "As at one moment there was a lot of noise coming from a specific stand, the team decided to train at the other side of the stadium, which was much quieter. A few players have heard sounds, which could be described as possible monkey chants. However, the training staff on the pitch were not aware of this."

While Van Bommel complained specifically of racist abuse, the Dutch FA had earlier said this was mixed with anti-Euro 2012 chanting believed to have been prompted by the fact the city has not been given any matches in the tournament. When this was put to Van Bommel on Thursday, he said: "Open your ears. If you did hear it and don't want to hear it, that is even worse."

Group Stages schedule:

• June 9: Metalist Stadium, Kharkiv - Arena Lviv, Lviv
• June 10: PGE Arena, Gdańsk - Municipal Stadium, Poznań
• June 11: Donbass Arena, Donetsk - Olympic Stadium, Kiev
• June 12: Municipal Stadium, Wrocław - National Stadium, Warsaw
• June 13: Arena Lviv, Lviv - Metalist Stadium, Kharkiv
• June 14: Municipal Stadium, Poznań - PGE Arena, Gdańsk
• June 15 : Donbass Arena, Donetsk - Olympic Stadium, Kiev
• June 16 : Municipal Stadium, Wrocław - National Stadium, Warsaw
• June 17: Metalist Stadium, Kharkiv - Arena Lviv, Lviv
• June 18 : PGE Arena, Gdańsk - Municipal Stadium, Poznań
• June 19 : Donbass Arena, Donetsk - Olympic Stadium, Kiev