People were queuing outside the terminal from early in the morning.
Dublin Airport Authority has confirmed that over 1,000 people missed flights on Sunday due to large queues at the airport.
Speaking on
RTÉ's Morning Ireland, daa's Head of Communications, Kevin Cullinane said an official figure on those who missed flights will be established on Monday morning.
"At this stage we estimate over 1,000 passengers," Cullinane said.
"We will be doing a final tally with all our airline partners and customers again this morning to ascertain the final number."
He added: "But certainly at this stage, it’s well over 1,000 passengers, and we unreservedly apologise."
Cullinane said the airport was operating at the max of its available staffing levels, and was operating on "very fine margins.
"Yesterday morning when we opened security in terminal one and terminal two, we clearly didn't have enough security lanes open due to resourcing challenges, and at the moment any absenteeism impacts on our ability to operate lanes," he said.
370 additional officers are due to start in the airport over the coming weeks.
On Sunday, some passengers were queuing outside of the terminal at Dublin Airport since early morning as part of contingency plans to reduce the risk of missing flights.
The airport said it had been experiencing significant queues during check-in, bag drop, and security screening.
Cullinane said that while the airport would be aware of how many passengers are due at the airport over the course of a day, it does not receive airline manifests and only became aware of the extent of the issue around 4am on Sunday.
He added that anyone who is out of pocket as a result of yesterday's queues will be reimbursed as quickly as possible and should email
customerexperience@dublinairport.com.
