The Kick It Out campaign says it considers the idea to have extremely xenophobic and nationalistic overtones.

Mr Hammam, a Lebanese businessman and the former Wimbledon owner, proposed the idea to boost loyalty among Cardiff supporters and Welsh fans generally.

Under the scheme, to be launched on March 1 - St David's Day - supporters would be sold a Cardiff shirt for half price if they handed in a rival English team strip.

Mr Hammam initially said the rival teams' shirts would be burned, but due to wide condemnation the club said this was no longer the case.

A club spokesman said: "The idea is to get people to wear Welsh club shirts rather than any other football club shirts. Sam Hammam's view is if you are Welsh, why are you wearing a Manchester United or a Barcelona or any other shirt when you should be wearing a Welsh football club shirt?"

But Piara Powar, national co-ordinator for Kick It Out, called the scheme "dangerous and foolhardy".

Mark Evans, spokesman for the Football Association of Wales, said: "We are looking into it. We are not happy with how this has been approached".

And Chief Superintendent Gerry Toms, of South Wales Police, said: "I certainly do not support the proposal and believe it needs a rethink".