Euro 2012: Uefa acknowledge 'isolated' racist chants directed at black Holland players during training session Their statement continued: "Should such behaviour happen at further training sessions, Uefa would evaluate the operational measures to be taken to protect the players. 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. It is understood Uefa's stance changed following lobbying from the FARE (Football Against Racism in Europe) network. The chief executive of European football's leading campaign group against racism, Piara Powar, said: "Van Bommel has no reason to invent such a claim. It's quite clear it happened. And if there's some confusion within the governing bodies, the KNVB or Uefa, then that's regrettable. In our view, the incident took place. He added: "If the captain says, 'My team-mates were racially abused, I heard it, I was there at the ground level', then one expects any FA to back the captain. We're very clear with Uefa that any incident of this kind needs to be looked at. The Dutch FA were not immediately available for comment but reports claim they will not make a formal complaint and consider the matter closed. Uefa were yesterday satisfied by claims the abusive chanting from the stands was actually a protest against the fact Krakow had not been made one of the host cities for Euro 2012. Another theory put forward was that Wisla's supporters did not want their stadium being used by anyone but their own club and were simply booing the Dutch players. The problems reportedly occurred when players began Wednesday's training session by doing laps of the pitch only to be greeted at one end of the stadium with monkey noises and loud jeers. Van Bommel told anyone who denied it was racially-motivated to "open your ears," adding: "If you did hear it, and don't want to hear it, that is even worse." There were already fears over racism at this summer's tournament, with BBC's Panorama programme last week highlighting the problem at Krakow's two major clubs, Wisla and Cracovia, as well as in Ukraine. Mario Balotelli - whose Italy side are also based in Krakow - had threatened to walk off in protest if he was racially abused during games but Platini warned any player who did so would be yellow-carded. Powar called on teams to play their 'open' training session behind closed doors if necessary. He said: "Public displays of intolerance like this - xenophobia, anti-semitism and racism - can't be allowed to go on. If that means playing behind closed doors and closing down that whole open-training system then I think that needs to be done. Powar said on Wednesday he was more concerned about Euro 2012 than any previous tournament because of the well-documented problems with racism and anti-semitism in Poland and Ukraine. He added today: "It's a great shame for this to happen on the eve of the tournament." Action Uefa could take is understood to include ejecting fans as well as tighter security checks and increasing steward numbers.