Uefa admit it will be difficult to find "hard evidence" to punish allegations of racism towards Benni McCarthy during Blackburn's clash against Wisla Krakow in Poland.

Blackburn's dramatic Uefa Cup group stage win was overshadowed when South Africa striker McCarthy squared up to Serbian defender Nikola Mijailovic as the final whistle sounded.

Rovers will contact Uefa over the matter and Europe's governing body are waiting for reports from the referee and match delegate before deciding whether sanctions are required.

If found guilty, punishments range from a warning to disqualification from a future competition, although Uefa director of communications William Gaillard sees problems in finding evidence to back up the claims.

He said: "Benni McCarthy has been in the game for a long time now, playing at the top level, so we have no reason to doubt his word. The problem will be finding the hard evidence to pass sanctions.

"There is always the problem of finding hard evidence but at the same time the referee might have heard something. It should be in the referee's report and I heard that Blackburn people mentioned it to the delegate."