Passengers flying into the airport at the weekend reported having to wait for up to three hours before clearing passport control. But after leaflets apologising for the problem were handed out by BAA, which owns Heathrow, the UKBA warned that they were "inappropriate" and that ministers would take "a very dim view".

The airport operator was also told to prevent passengers taking pictures in the arrivals hall, according to the Daily Telegraph, which obtained correspondence from Marc Owen, director of UKBA operations at Heathrow. Pictures of lengthy queues have been posted on Twitter by frustrated travellers.