Belfast International Airport has apologised after scores of passengers were stuck in long queues on Friday morning, with some missing their flights.
Pictures from the scene circulating on social media show queues stretching through the security area and down the stairs.
One Twitter user said there was only one member of staff dealing with the large crowds of passengers.
A Belfast International Airport spokesperson said they have made a "significant investment" in the security area in recent months and increased staffing numbers, however they recognised some passengers had a "difficult experience" and apologised.
A lot of people missed their flights today. Iâve been in airports all over the world and never ever saw a queue all the way from security to the airport entrance. It was crazy.— Ash Clarke (@AislinnClarke) August 2, 2019
Many passengers took to social media to vent their frustration at the situation.
One Twitter user wrote: "Absolutely ridiculous that we are back to excessive queues at security with people missing flights."
"Even on good days travellers need to arrive super early in case 'today' happens. Daughter nearly missed her flight, others did miss their flight," said another.
*One* member of staff at Belfast International Airport, dealing with *this* queue. 🙈 (Yes, it goes right down the stairs.) pic.twitter.com/10Q1DA8PRX— Michael Pierse (@michaelpierse) August 2, 2019
One passenger who missed her flight because of the queues said: "A lot of people missed their flights today. I’ve been in airports all over the world and never ever saw a queue all the way from security to the airport entrance. It was crazy.
"I fly almost every other week from this same airport. I left in good time as always. They had one person managing a queue that was going all the way from security to the airport entrance. It was an extraordinary situation and a lot of people missed their flights."
Be very early for your flights at Belfast International Airport. Took one hour to get through security this morning at 5am. Never seen it so bad.— Latte Larry's (@Dene71) August 2, 2019
A Belfast International Airport spokesperson said: “Over the last few months we have made significant investment in the security area and process as well as increased staffing numbers.
"Passenger satisfaction levels have increased dramatically a a result of this, however, we do recognise that some passengers had a difficult experience this morning and we sincerely apologise for the inconvenience caused.”