Police checking security at Wembley Stadium for the Olympic Games have lost a set of keys, it has emerged.

Officers searching the venue ahead of the start of events misplaced the keys, prompting an investigation by Scotland Yard.

Games organisers insisted that security had not been compromised by the incident, and stressed that the keys were internal and that the relevant locks have now been changed.

Scotland Yard is not treating the incident as criminal.

In a statement, the Metropolitan Police said: “On the morning of Tuesday 24 July officers on Olympic police operations at Wembley Stadium reported that internal security keys, being used by them as part of searches, were missing.”

It added that fellow officers attended the scene to help look for the keys but nothing was found.

The news comes a day after spectators attending the Olympic football games at the stadium complained of “ridiculous” queues for food and drink after some tills stopped working.

Fans hoping to buy snacks as they watched Great Britain's men take on United Arab Emirates were told they could not pay by Visa, the only credit or debit card accepted at London 2012 venues, and must use cash.