Border Agency official condemns staff shortages
Immigration officers from Manchester have been rushed to Heathrow as passengers arriving at Britain's premier airport report long delays.
London Mayor Boris Johnson has raised concerns about the Olympics - saying the queues give a "terrible impression of the UK".
And a border agency employee has told the BBC that staff shortages are affecting security checks. But ministers insist security is paramount.
The BBC's Home Affairs Correspondent, Tom Symonds reports.