Passengers flying into Heathrow on Saturday reported having to wait for up to three hours before clearing passport control. The issue has become a major government concern in the runup to the Olympics, with immigration minister Damian Green being summoned before the home affairs select committee about the problem.

But the Public and Commercial Services union has warned staff cuts at the Border Agency will make tackling the queues difficult, with 1,500 staff going by 2014. The union's general secretary Mark Serwotka said: "We've warned time and time again that, as elsewhere in the public sector, cutting jobs in UKBA is not only unnecessary, it's hugely damaging. Quite clearly, there are not enough staff."