G4S say they could lose as much as £50million as a result of the London Olympics security fiasco.
In a statement, the company said it "deeply regrets" the problems which have resulted in 3,500 troops being drafted in at the 11th hour to make up a shortfall in security guards for London 2012, which is just two weeks away.
"G4S accepts its responsibility for the additional cost of the increased military deployment resulting from the shortfall in workforce delivery," the statement said.
"The company is also incurring other significant costs as it endeavours to meet the contract challenges.
"Whilst it is not possible to gauge the precise financial impact, it is estimated that the company will incur a loss on the contract in the range of £35 million to £50 million, all of which will fall in the current financial year."
Chief Executive Nick Buckles expressed regret that G4S had been unable to meet its commitment to Locog to provide security guards.
"We are deeply disappointed that we have not been able to fully deliver against our contract with Locog and that it has been necessary to call upon the additional military personnel," he said.
"In partnership with the military and Locog, we are working flat out around the clock to resolve the situation. We are determined that together we will deliver a successful and secure games."
G4S, whose contract was worth £284m, claimed it had run into difficulties in processing applicants in sufficient numbers through the necessary training, vetting and accreditation procedures in what it described as "an extremely complex workforce supply contract".
"As a result, we will be unable to deliver all of the necessary workforce numbers," the statement added.
"We have worked very closely with Locog throughout the build up. At the point we felt that we could no longer assure the scale of the security workforce we had committed to, we advised them of the situation."
Prime Minister David Cameron had said on Friday that firms who failed to deliver on their contracts for the Olympics should have to bear the cost.
"I'm absolutely clear that if companies don't deliver on their contract then they should be pursued for that money," said Mr Cameron.