Britain's Olympic security chief says the private contractor that was unable to provide enough guards for the Summer Games had failed to disclose its problems in the buildup to the event.

Home Office head of security and counterterrorism Charles Farr told a committee of lawmakers Tuesday that G4S had not been "completely open" with organizers before the July 27 opening.

G4S admitted in early July that it could not provide all 10,400 contracted guards, forcing the government to call in thousands of troops.

Farr said that just days before the admission, G4S had sent the government "sets of data which gave no indication whatever ... that there was going to be a problem."

G4S says that failing to fulfill its contract has cost it 50 million pounds ($79 million).