Hundreds of Manchester City tickets to the English soccer club’s April 16 Football Association Challenge (FA) Cup semi-final were stolen from a mail truck recently, disappointing fans who were awaiting their delivery.

The stolen tickets have been cancelled and duplicates have been issued. But, the frustration does not end there; it is likely that many more will face problems at Wembley Stadium on game day when they find that those tickets, purchased from “touts” on the black market, are invalid. In the UK, ticket resellers are often referred to as touts.

Last week, thieves stole two bags of special delivery mail containing roughly 900 tickets destined for Manchester City club members for the much-anticipated semi-final match against arch rival Manchester United. The bags were stolen on the evening of April 1 from a Royal Mail (British postal service) truck near the club’s Eastlands grounds. Following the theft, the Greater Manchester Police raided a number of addresses connected with the investigation, and yesterday, April 5, authorities announced the arrest of an unnamed 39-year-old Royal Mail employee, who soon after was released on bail.

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The theft comes at a time when primary and secondary ticketing in the UK is the focus of much media attention. The 2012 London Olympics, which is gearing up to begin selling tickets, is a little over a year away, and separately, a Member of Parliament has proposed legislation to regulate secondary ticket sales.

As of Tuesday evening, April 5, none of the stolen tickets has yet been recovered, and the investigation into the theft continues. The fierce rivalry between Manchester City and Man U makes these tickets particularly popular, which led authorities to worry that they will make their way, if they haven’t already, to the black market.

Manchester City published a statement on their Web site this week, warning fans to avoid buying tickets from any vendor other than the team. In the UK, major professional soccer teams must give their approval for an entity to resell their tickets.

“Wembley Stadium will re-issue the stolen tickets to the Club, meaning that we will have our full allocation. Supporters are again reminded not to purchase tickets from unofficial sources. Only tickets purchased direct from the club will be valid for the game,” the statement read.

The FA has also taken steps to reduce the possibility of fraud in connection with the stolen tickets and was quoted in the club’s statement on their site: “The original tickets that were stolen have been cancelled on the stadium’s access control system. Only the tickets for these specific seats that are now being re-issued to Manchester City will be valid on that day.”

The barcodes on the original tickets have been invalidated, making them worthless on game day. Manchester City fans who paid for these tickets and who were awaiting their delivery will be contacted by the club regarding the reissue in the coming days.

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Despite the proactive steps taken by the stadium, the club and the FA, game day is still likely to see considerable chaos as those who’ve bought the invalidated tickets show up, probably by the hundreds, right in the middle of a very busy sports weekend, which includes more playoffs at Wembley and the London Marathon on April 17.