A fault on UK Border Force computers, including automatic passport check-in desks, caused systems to crash late this evening, causing widespread chaos for passengers at airports such as Heathrow, Gatwick, Stansted and Birmingham.
Extra staff were drafted in to try and reduce the queues.
Passengers tweeted their frustration through the evening:
A Government spokesman said: "We apologise for any additional time this adds to passengers' journeys."
More top news
Criminal gangs are circumventing the UK's strong gun control laws by using antique weapons and homemade ammunition, investigators warned.
Tempers flared on Good Morning Britain as television host Piers Morgan calls the former Chelsea footballer, "a sexist pig".
The Cabinet Secretary is expected to return to his post in September.