The 2012 Olympic Games have run £2bn over budget, according to a report by the Commons Public Accounts Committee.
MPs have criticised organising committee Locog over the spiralling costs, which now amount to an alleged £11bn, as well as poor security planning.
"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," said committee chair Margaret Hodge.
"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."
The 2012 Olympic Games were initially given a budget of £2.4bn when London won the bid to host the event in 2007, but the figure rose to £9bn within two years.
A Department for Culture, Media and Sport spokesman rejected the latest figures, claiming that the cost will eventually be returned to the public purse.
"The cost of purchasing the Olympic Park land will ultimately come back to the public purse through the resale of the land after the Games and was therefore not included.
"Funding for the legacy programmes, that the committee refer to, comes from existing business-as-usual budgets and we have been clear about this.
"These are for projects designed to capitalise on hosting London 2012 but are not an additional Olympic cost.
"We are completely committed to delivering on Lord Coe's promise to use the Games to inspire a generation to choose sport."
The 2012 Olympic Games opening ceremony takes place in London on July 27.
Mark Langshaw
