Passengers arriving at Heathrow were forced to wait in long queues on Wednesday or were held on planes due to a problem with self-service passport gates.
The airport has been plagued with incidents of slow-moving queues and delays at Border Control this year.
Heathrow has attributed the problems to the Border Force, which is run by the Home Office.
Last week an unnamed Border Force guard told that the recurring problems with Border Control were due to a “nightmare” new rota system for guards, increasing working hours and causing some officers to quit their jobs or call in sick.
Heathrow says the Border Force failed to achieve its monthly target six time last year.
A spokesperson for the Home Office said: “This morning a technical issue affected e-gates at a number of ports. The issue was quickly identified and has now been resolved. We have been working hard to minimise disruption and continue to monitor the situation closely.
