Undercover police officers smuggled a fake bomb into the London 2012 Olympics site in order to test security, it has been reported.
The news emerged on the day David Cameron hosted a special Cabinet meeting to mark 200 days until the Summer Games.
The dummy run saw officers carry the “device” around the Stratford Olympic Park last year, the Evening Standard reported.
The test was carried out to check electronic and human surveillance systems at the site.
Police have refused to reveal details of the breach but a spokesman for the Olympic Delivery Authority said it was working with the Met to improve security.
He said: “Such tests have a key role in developing our capability to ensure that London 2012 is safe and secure and that we are best prepared to detect potential threats before and during the games.
“Members of the public with tickets should be reassured that such exercises are being staged to ensure their safety, our number one priority.”
Peter Fussey, author of “Securing and Sustaining the Olympic City”, told the Associated Press the only unusual thing about the reports was that the public had heard about them.
He said: “You can’t make something completely terrorist-proof. There’s always going to be some risk.”
Margaret Gilmore, a senior research fellow at the Royal United Services Institute, said the point of the test was to expose vulnerabilities.
“The key thing is that they are putting this real ring of steel around the Olympic sites,” she said.
Today it also emerged small attack helicopters known as “killer eggs” will be deployed across the capital during the Olympics.
The Evening Standard revealed SAS and SBS commanders will borrow the aircraft from US special forces to help combat terror attacks.