G4S boss: 'Disappointed' [Nick Buckles © SKYnews]

The chief executive of G4S Security has said he is sorry and bitterly disappointed that the firm cannot provide enough security guards for the London Olympics.

The security firm has said it stands to lose up to £50m and has accepted responsibility for the costs of extra military personnel that will now be used at the Games.

Chief Executive Nick Buckles has been asked to appear before the Home Affairs Select Committee next week.