Passengers at Liverpool John Lennon Airport had to leave the departure lounge and go through security again after a technical problem was discovered with a scanning machine on Friday.
The airport stressed there was no threat to passenger safety.
But it said the rescreening process was necessary in order to ensure security compliance.
A spokesman said around 1,000 people had to pass again through security checks when the discovery was made on Friday afternoon.
He said although this was done quickly, it caused delays to some flights.
