Passengers travelling to the London Olympics could face four-hour queues at airports, the head of the UK Border Force admitted.

Brian Moore said he did not believe there would be a repeat of the recent chaotic scenes at Heathrow when 600,000 extra visitors arrive for the Games. But he refused to rule out protracted delays. "There will always be circumstances beyond our control. There could always be conditions which arise," he told the Commons Home Affairs Select Committee.

Mr Moore denied that temporary staff being drafted in to border posts in July and August would receive less training than their permanent colleagues.