The total cost of the 2012 Olympics has risen from £9.3 billion to £11 billion because of security reasons, according to the Public Accounts Committee, Parliament of UK.
The London 2012 Organising Committee (Locog) now needs twice the number of security guards it originally estimated and the costs have roughly doubled.
Locog's initial estimates of the cost and scale of venue security were based on a "finger in the air estimate", according to the PAC.
Initially, Locog had put the number of security men needed at 10,000 to 23,700, but their numbers have more than doubled. Consequently, the total cost to the Public Sector Funding Package of venue security has nearly doubled from £282 million in 2010 to £553 million in December 2011.
"Locog now needs more than twice the number of security guards it originally estimated and the costs have roughly doubled. It is staggering that the original estimates were so wrong. Locog has had to renegotiate its contract with G4S for venue security from a weak negotiating position and there is a big question mark over whether it secured a good deal for the taxpayer," said Margaret Hodge MP, Chair of the Committee of Public Accounts, told Guardian.
"Taking into account costs outside the package, the full cost to the public of the Games and legacy projects is already heading for around £11bn," she said.