Consumer group Which? is suing high street retailer JJB Sports on behalf of fans who were unlawfully overcharged for football shirts.

Which? says it is taking the retailer to court to claim back money for people who were unlawfully overcharged for football shirts in 2000 and 2001 by a cartel made up of JJB Sports and six other companies.

The companies were fined a total of over GBP16m (US$31m) in 2003 by the Office of Fair Trading for fixing the price of England and Manchester United football shirts in 2000 and 2001.

Malcolm Coles, online editor, Which?, says: "JJB Sports and their fellow cartel members tried to ensure the market was all sewn up, so it would have been difficult to find these shirts for sale at a fair price.

"Although JJB has already paid a fine, the money went to the government. We're suing now to try to get money back for the people who paid more than they should have - and whose money only went to line this greedy cartel's pockets.

"This case is as much about justice and fairness as anything else. We want to teach companies that rip off their customers a lesson."

The consumer group is now calling on people who bought certain shirts during 2000 and 2001 to come forward and register a claim on www.which.co.uk/football-shirts - even if they no longer have a receipt.

Which? has issued proceedings in the Competition Appeals Tribunal (CAT) to start the case, and a case management conference (CMC) will be held to determine how the case will proceed.

The other companies fined by the Office of Fair Trading in 2003 were Allsports Ltd, Blacks Leisure Group Plc, Manchester United Plc, Sports Soccer Ltd, JD Sports, and Umbro Holdings Ltd.