Ryanair and Aer Lingus have cancelled a number of flights because of industrial action by French air traffic controllers.
Aer Lingus said customers who have bookings on the cancelled flights may change for free online to another date of travel or may request a full refund.
The airline also said there may be delays to flights which use French airspace. A full list of cancelled flights can be found on the company's website.
Ryanair said: “Unfortunately, further flight delays and cancellations are likely and customers are asked to please monitor this notice which will be updated throughout the day.
“We sincerely apologise for any inconvenience caused by these unjustified ATC disruptions which are entirely outside of our control.”
The airline said customers could apply for a refund or change their flight dates for free.
A full list of cancelled flights can be viewed on Ryanair's website.