Plans to use drug sniffer dogs at the Madejski Stadium were dealt a blow when news of the police operation was leaked to the Manchester United squad in advance of the game. Sir Alex Ferguson faxed the club warning that they would be unable to fulfil the fixture if the checks went ahead.

The fax read: "We are very sorry to inform you that we will not be able to field a full team from our first team squad for Saturday's match. Once news about your plans to drug test people entering the stadium spread around our training facility, Rio Ferdinand slipped out of the ground telling his team mates he was going shopping and that his mobile would be off. We apologise for any inconvenience."

Martin Salter, the Supporters Trust at Reading (STAR) Vice-President and supporter of cannabis liberalisation, has denied putting pressure on the club by refusing to go to matches unless they called off their dogs.