G4S says it will meet the full cost of deploying thousands of extra troops to the London Olympics after it failed to supply sufficient numbers of security guards.

In a statement, the company disclosed that it stood to lose up to £50 million on its £284 million contract with the Games organisers, Locog, as a result of the fiasco.

Chief executive Nick Buckles confirmed that they would be facing a penalty payment "in the range" of £10 to £20 million as a result of the firm's failure to meet its commitments.

However he said that the bulk of the loss would come from paying the Ministry of Defence to supply 3,500 additional troops to make up the shortfall.

"We accept that we underestimated the task of supplying staff for the Olympics. We deeply regret that," Mr Buckles told the BBC Radio 4 Today programme.

It emerged on Wednesday evening that additional troops would be required after G4S admitted that it would not be able to deliver the 10,000 security guards it was contracted to provide.

Despite having signed the initial contract in 2010, Mr Buckles said that he had only realised "eight or nine days ago" that there would be a shortfall in the numbers.

"We are recruiting a large number of people, they are all working through a process of interview, two or three different degrees of training, licensing, accreditation," he said.

"Our review process was around the number of people applying for interviews, we had 100,000 of those, the number of people interviewed which was 50,000.

"So basically you work through that process of numbers and as they were getting ready for deployment over a period of time, it's only when you get closer and closer to the Games that your realise that the number isn't as high as you expect."