The head of security company G4S has said he regrets it ever took on the Olympic security contract, as he agreed it had become a "humiliating shambles".
The company may lose £50m from the £284m contract because it cannot supply enough security guards.
Chief executive Nick Buckles told MPs that the military and the police would be reimbursed for providing personnel to plug the shortfall.
But he said G4S planned to keep its £57m management fee.
Mr Buckles said that because the firm expected "to deliver a significant amount of staff" it would retain the fee.
"I find that astonishing," replied Labour MP Keith Vaz, who chairs the Commons home affairs select committee.
Mr Buckles also told the committee the cost of accommodation for military personnel called in to help would be covered and bonuses would be paid to them if this was deemed appropriate.
G4S has been under fire since it emerged last week that 3,500 extra military personnel have had to be deployed to meet the firm's shortfall in trained security guards for the Games. Police have also helped fill gaps left by G4S.
Ministers insist the security of the Games will not be compromised.
A spokesman for Prime Minister David Cameron said: "We need to focus on working with G4S to ensure a safe and secure Games. We have confidence we have plans to deliver a secure Olympics."
Meanwhile a decision on whether G4S will be given contracts to operate any more prisons in England and Wales has been put back until the autumn.
G4S is competing against other private sector firms and the Prison Service for four of the six contracts which have been put out for tender, involving eight publicly-run jails and one in the private sector.
The Ministry of Justice had been expected to make an announcement before the summer recess but it has now delayed a decision until September.
Sources said the delay was not connected to the failure of G4S to provide enough staff for the Olympics.
There have been a number of developments as preparations for the Games continue:
- Tobacco Dock, an exhibition centre in Wapping, east London, will be used as accommodation for 2,500 of the 3,500 extra military personnel being deployed on Olympic security
- An insider from the committee organising the Olympics (Locog) has told the BBC that it failed to deal with the problems at G4S despite warnings over the last 18 months.
- London 2012 is withdrawing 500,000 Olympic football tickets from sale but 200,000 for other sports are to be made available
- Meanwhile, the Olympic torch has been passing through East Sussex and Kent on Tuesday
Earlier, during the committee hearing, Labour's David Winnick told the G4S chief executive: "It's a humiliating shambles, Mr Buckles."
"I cannot disagree with you," Mr Buckles replied.
He told MPs he was "very sorry" for what had happened.
When asked why he was still in the post, Mr Buckles said: "It's not about me; it's about delivering the contract. I'm the right person to ensure that happens."
The G4S boss said he had been told about recruitment problems by his team on 3 July.
He said as they "dug into data day by day we realised the pipeline and people we thought we could deliver, we couldn't".
Mr Buckles said he had been "shocked" to find this out and returned immediately from a holiday in the US.
He said it was on 11 July that he realised the contract would not be delivered - the same day Home Secretary Theresa May says she was informed of the problems.
G4S had been contracted to supply about 10,000 members of staff.
Mr Buckles told the MPs his company had about 4,200 people "working on the ground" and expected that at least 7,000 people would be in place for the Games.
"Clearly we regret signing it [the contract] but now we have got to get on and deliver it," he said.
He said that the contract had initially been more about the company building its reputation than the financial aspect.
Mr Buckles said the company was no longer bidding for the security contracts for the next football World Cup and the next Olympics, both of which take place in Brazil. He said the decision had been taken last week.