Croatian fans threw chairs, bottles and flares at Polish riot police in the city of Poznan as they clashed ahead of Sunday's Euro 2012 game between Croatia and Ireland.
Three people were arrested after the incident in Poznan's old town square, where thousands of Irish and Croatian fans, many clad in the national red-and-white checkerboard shirts, gathered ahead of the match.
The police said it would examine closed circuit video from the centre square to identify additional culprits. Croatia beat Ireland 3-1 in the Group C match.
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