MPs have hit out over the "predictable chaos" surrounding Olympic security - as the Government prepared to decide whether to deploy an extra 2,000 troops.
Ministers are being urged to "get a grip" on both the Games' organisers, Locog, and security contractor G4S - which has been slammed over its failure to recruit enough security guards.
Another 3,500 soldiers have already had to be drafted in after the beleaguered firm admitted it was not going to be able to provide the 10,400 guards it had promised, taking the full deployment to 17,000.
But a further 2,000, are allegedly also being kept in reserve as a contingency in case there are further issues.
A final decision on whether to officially put the extra troops on "notice to move" will reportedly be taken today - just eight days before the opening ceremony, according to a Home Office source.
But the Department for Culture, Media and Sport (DCMS) has been accused in an MPs' report of lacking transparency and not knowing how much security the Games needs.
Margaret Hodge, Public Accounts Committee chairwoman, said: "The chaos which has emerged over the security contract was predictable and undermines confidence in those responsible for managing the Games.
"There is now a last minute scramble to make sure there will be enough security personnel on the ground.
"In evidence to us before Christmas, all those concerned gave assurances that the contract could be met despite more than doubling the number of guards before the ink was dry on the original contract.
"No credible explanation has been given for an astonishing 12-fold hike in management costs, from £10m to £125m, and G4S still has not been able to deliver. Now troops are having to be drafted in.
"The Home Office needs to get a grip on Locog and G4S urgently.
"The Department would win no medals for transparency. We still don’t know just how many security guards will actually be delivered or whether G4S will face any penalty.
"We will carry out a post-mortem in September."
The potential further deployment will increase concerns about where soldiers are being housed for the duration of the Games and their living conditions.
But the Secretary of State for Culture, Olympics, Media and Sport , Jeremy Hunt disputed the report's findings.
"With just over a week to go we are on track to deliver a great Games on time and under budget," he said.
"At the end of May there was £476m of contingency unallocated and I am confident that we will deliver the project for under £9bn.
"We disagree with the Committee’s assertion that the DCMS has lacked transparency. London 2012 has arguably been more transparent than any other public sector project.
"For example, we have produced 16 financial updates to Parliament over the last four years."
A Home Office spokesperson has insisted no extra troops were due to be deployed - while the DCMS insists the cost of G4S's failure will not be passed on to tax payers.