A shortfall in G4S staff today hit the site of one of the first big Olympic events scheduled to take place.
Differing figures were given about how many workers were due to arrive at Box Hill in Surrey, and how many did so.
Chairman of the Commons Home Affairs Select Committee Keith Vaz said just 30 of an expected 300 G4S staff turned up.
He made the claim as MPs questioned head of G4S Nick Buckles and Ian Horseman-Sewell, the group's global events specialist.
But Mr Horseman-Sewell told the committee the company was supposed to provide 38 people for the event at 9am today. Organisers were told yesterday that the firm expected to provide just 17, he added.
Box Hill is on the route of the men's road cycling race, which takes place on July 28, a day after the opening ceremony, and will feature a British team including current Tour de France leader Bradley Wiggins and world champion Mark Cavendish.
Surrey Police said it was sticking to its established plans.
A spokeswoman said: "As of this week, Surrey Police has implemented its full Olympic policing plan, which includes supporting Locog's venue security operation.
"This has always been an established part of the plan and there is no longer the requirement to provide additional officers to enhance the security arrangements in place at this stage.
"As part of our planning for the Games, we have built contingency and resilience into our resourcing. This will continue to be available throughout the Olympic period."