More than 13,500 military personnel will be used to provide security during the London 2012 Olympic Games.

The Army, the Royal Air Force and the Royal Navy are expected to provide service personnel who will make up an estimated 23,700 security staff which the Department for Culture, Media and Sport thinks will be needed to police the Olympic Games. It is more than double the original 10,000 estimate.

Ministers have also revealed that the security budget has gone up from �282 million to �553 million.

Defence Secretary Philip Hammond said although the Games would present the “biggest security challenge” for decades, the military deployment had become routine since the 1996 Atlanta Olympics.

Snipers in helicopters, based on HMS Ocean in the Thames, near Greenwich, are expected to patrol the skies over the capital during the Games when Typhoon fighter jets will be based at RAF Northolt in London.

The MoD will also provide specialist support for civilian authorities with special forces, bomb disposal capability and military search capabilities and specialist sniffer dogs.