Aer Lingus regional flights operated by Stobart Air have been impacted after Stobart Air announced it has ceased operations.
Aer Lingus said the airline informed them last night it was terminating its franchise agreement with Aer Lingus and was in the process of appointing a liquidator.
Aer Lingus said it could not say how many customers are affected but apologised and said it "is doing everything it can to accommodate customers with rebooking and refund options".
There are 12 routes scheduled to operate that have been immediately impacted by the decision.
Aer Lingus said all impacted customers were being contacted directly and offered details of an alternative flight where feasible. All impacted customers also have the option of a full refund, it said.
Among the first flights to be cancelled were the 9.10am from Dublin to Glasgow and the 12.25pm from Dublin to Kerry this afternoon.
This evening, Aer Lingus announced details of a replacement schedule for Aer Lingus Regional customers. Of the twelve routes immediately impacted by Stobart Air's decision to cease trading, Aer Lingus said it will operate five routes and for at least the next week BA City Flyer will operate two.
Full details of the Aer Lingus Regional replacement schedule can be found on the Aer Lingus website.