Soccer:Uefa today vowed to crack down on racism at the European Championship after acknowledging that the Netherlands' black players were abused during a training session in Krakow.

Members of Bert van Marwijk’s European Championship squad were allegedly subjected to monkey chants at Wisla Krakow’s Miejski Stadium on Wednesday, with captain Mark van Bommel yesterday branding the incident “a real disgrace”.

Having been satisfied by the Dutch Football Association’s initial assurances the abuse was not racially-motivated, Uefa announced this morning they had been made aware of “isolated incidents of racist chanting”.

European football’s governing body confirmed they would consider increasing the number of stewards at open training sessions in order to eject fans if there was a repeat.

They said in a statement: “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.

“Uefa has not yet received any formal complaint from the KNVB. 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 statement followed lobbying from the FARE network. The chief executive of European football’s leading campaign group against racism, Piara Powar, said: “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.”

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.”

A Dutch FA spokeswoman was quoted as confirming some of their players did hear monkey noises but it was also reported a formal complaint would not be made and that the matter was considered closed.

Former Dutch star Ruud Gullit, now a Uefa representative, said today: “Everybody was very, very upset”.

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.

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.

The abuse was said to be bad enough for the squad to move their equipment and training drills as far away as possible from the affected area.

Van Bommel told anyone who denied the incident was racially-motivated to “open your ears”, adding: “If you did hear it, and don’t want to hear it, that is even worse.”

The Netherlands travelled to Kharkiv, Ukraine, today and were scheduled to hold a press conference ahead of their Euro 2012 Group B opener against Denmark tomorrow.

There were always 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.

Uefa president Michel Platini said on Wednesday referees would halt or even abandon matches if there was serious racism from the stands during Euro 2012.

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.

The families of two of England’s black players, Alex Oxlade-Chamberlain and Theo Walcott, have already decided against travelling to the tournament because of the potential problems.

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.”