London (CNN) -- The bill for staging the 2012 London Olympics and Paralympics is set to rise by nearly 20% to £11 billion ($17.2 billion) a UK government committee has warned.
The £9.3 billion ($14.5 billion) of public money set aside for funding the Games is "close to being used up" according to a report published Friday by the British Parliament's public accounts committee.
"We are concerned about whether the running of the Games will be held within budget. Taking into account costs outside the package, the full cost to the public of the Games and legacy projects is already heading for around £11 billion," said Margaret Hodge MP, chair of the committee.
Hodge said that the committee were "particularly concerned" with the rise in cost of security for the Games which has doubled from the 2010 estimate of £282 million ($442 million) to over £550 million ($862 million) by December 2011.
The London Organizing Committee of the Olympic Games (LOCOG) early estimate of a need for 10,000 security guards has now jumped to 23,700.
"It is staggering that the original estimates were so wrong," Hodge said.
The committee also raised concerns about the Olympic stadium becoming "a white elephant."
As yet, no takers have been found for the 80,000-capacity venue which is estimated to have cost nearly £500 million ($785 million) to build.
A deal which would have seen West Ham Football Club move into the stadium after the Games collapsed in October 2011.
A new tender process opened in December last year with interested parties required to submit full bids by March 23 2012.
The committee also expressed concerns about the UK Government's legacy commitment.
"We were promised a strong Olympic legacy but the Government has chosen not to adopt the target of one million more people participating in sport by 2013," Hodge said.
But Hugh Robertson, the government's minister for sport, rejected the committee's findings.
"What (the committee) has not done is made any allowance for the amount of money that comes back to the public purse once the land on the park has been sold," Robertson told the BBC.
Should the committee's estimates be borne out, the projected cost of staging the Games will have almost trebled from an initial bid estimate of £4 billion ($6.3 billion).
That figure was revised up to £9.3 billion in 2007.
The Olympics and Paralympic Games get underway on July 27 and August 29 respectively.