Denis Oswald, the chairman of the IOC's co-ordination committee for London 2012, told Telegraph

"It's really a difficult budget. Compared to previous Games, it is really rocketing. I would think it would be the biggest spend on security in Olympic history. It is sad, because you think of all the other things that the money could be spent on, but that is the evolution of the world, Oswald said ahead of a lecture at De Montfort University in Leicester.

"Athens spent Euro 900 million (780 million pounds), and brought in support from different countries as well. In the lead-up to 2004, there was an attack in Istanbul, as well as the bombings in Madrid. Nobody knows how much it will cost London in the end, because it all depends on the situation: a few attacks like the one in Mumbai, especially if they are closer to this country, and they will have to reinforce security again," he added.

The security budget for the London Games was stepped up in December last year, when an additional 238 million pounds contingency fund was added to the 600 million pounds already earmarked for the purpose.