Dublin Airport saw a second day of disruption to its check-in and baggage drop in Terminal 2 following yesterday's cyber attack which impacted several airports across Europe.
Airport operator daa said it is continuing to support airlines as they deal with the ongoing disruption.
Aer Lingus said that the incident had "significantly impacted operations", with 13 flights cancelled today. Nine of these were inbound flights, with four outbound.
It is understood that a number of IT experts from the US are to fly into Dublin this evening to check the systems here.
In a statement issued this evening, daa said: "IT teams working hard to restore systems which will allow for normality to resume.
"This will continue tonight - we're hopeful that a full fix isn't far away but there is a chance that manual processes may be required again for the first wave tomorrow morning for some airlines.
"Airlines have aircraft where they need to be, so full schedules expected to operate.
"Some airline processes in airport - check in and bag drop - may still take a bit longer than normal so passengers should plan ahead and give themselves extra time where they can."
A cyber attack at a provider of check-in and boarding systems yesterday disrupted operations at several major European airports including London's Heathrow, the continent's busiest, causing flight delays and cancellations.
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Daa said check-in and boarding systems were impacted today, as some airlines had to use manual workarounds to generate bag tags and boarding passes.
"This means that the check-in and bag drop processes may take slightly longer than normal," daa said.
Yesterday's evacuation of the airport following a security alert was unrelated to the cyber attack, daa said.
London, Brussels and Berlin airports also experienced delays and disruption following the "technical issue" affecting Collins Aerospace, which works for several airlines at multiple airports across the world.
The disruption began on Friday night and continued throughout yesterday, with flights cancelled or delayed as the impacted airlines had to carry out check-in and boarding operations manually.
Passengers due to fly from the London Heathrow's Terminal 4 said they were met with queues, delays and confusion as to whether they'd be able to make their planned trips.
Heathrow said passengers should check their flight status before travelling to the west London airport.
"Work continues to resolve and recover from Friday's outage of a Collins Aerospace airline system that impacted check-in," Heathrow said.
"We apologise to those who have faced delays, but by working together with airlines, the vast majority of flights have continued to operate.
"We encourage passengers to check the status of their flight before travelling to Heathrow and to arrive no earlier than three hours for long-haul flights and two hours for short-haul."
It is understood British Airways at Terminal 5 remains unaffected and has been operating as normal.
Around 14 flights were cancelled and some delayed across the other terminals on Saturday, although it is not clear which of these were caused by the technical issue.
Brussels Airport said: "As a result of a cyber attack on the external service provider of the check-in and boarding systems, check-in operations at several European airports, including Brussels Airport, are heavily disrupted.
"The service provider is actively working on the issue and trying to resolve the problem as quickly as possible.
"This has a large impact on the flight schedule and will, unfortunately, cause delays and cancellations of flights."
A statement on the Berlin Airport website said there were longer waiting times at check-in.
Collins Aerospace said yesterday it was working to resolve the issue as soon as possible.
It said: "We have become aware of a cyber-related disruption to our Muse (multi-user system environment) software in select airports.
"We are actively working to resolve the issue and restore full functionality to our customers as quickly as possible. The impact is limited to electronic customer check-in and baggage drop and can be mitigated with manual check-in operations."
The European Commission, which takes part in managing airspace across Europe, said it is monitoring the situation but added there were no signs the cyber attack was "widespread or severe".
