Border Force managers have been accused of using barely trained staff to fill posts on immigration desks so that the government could meet its pledge that all desks would be filled during high-pressure periods for Heathrow.

Staff insiders have reported that officers who had not been fully trained were asked to stand in for colleagues at times when photographs were to be taken to prove that staffing levels were being maintained.

Immigration minister Damian Green made the pledge with the Olympics in mind after rows over long delays for passengers at Heathrow in the spring, but whistleblowers allege that inexperienced staff had to fill the gaps.