Organisers for the London 2012 Olympic Games have revealed that they have oversold tickets for the synchronised swimming event, amounting to 10,000 too many.

Thousands of successful applicants, who acquired the tickets during the second sale window in June, have been contacted by the organisers with the option of an alternative event.

The mistake was down to the ticketing system, which claimed that 20,000 spots were still available for synchronised swimming, when in reality half of that number were left over the four sessions of the event.

A spokesman for the London Organising Committee of the Olympic and Paralympic Games said: "As a result of finalising the seating configurations in our venues and reconciling the millions of Olympic and Paralympic ticket orders against the seating plans for around 1,000 sporting sessions, we have discovered an error in seats available in four synchronised swimming sessions."

Up to 3,000 applicants have been offered another event instead of the swimming.