The cost of policing rallies by the English Defence League (EDL) and their opponents in a Shropshire town last month was £342,500.
The home secretary had banned a planned EDL march in Wellington amid fears of disorder but about 400 people from opposing groups still went to the town.
More than 40 people were arrested as rival groups clashed on 13 August.
A report to West Mercia Police Authority said £300,000 was spent on bringing in officers from other forces.
The match between AFC Telford United and Luton Town, due to be held on the same day in Telford, was also postponed because of fears of trouble.
The report by Chief Constable David Shaw said three police officers were assaulted during the clashes but none were seriously hurt.