Hundreds of flights have been cancelled this week as crew in Belgium, Spain and Portugal walked out, affecting more than 100,000 customers.
Additional industrial action is being taken by Irish pilots, who are planning a fourth day of action next month.
But Ryanair is insisting the strikes by cabin crew don’t fall under EU rules.
A Ryanair spokesperson said: “Ryanair fully complies with all EU261 legislation, however as these flight cancellations were caused by extraordinary circumstances, no compensation is due.
“Under EU261 legislation, no compensation is payable when the union is acting unreasonably and totally beyond the airline’s control.”
But the CAA said passengers have the right to seek compensation under EU legislation as Ryanair did not give enough notice.
An earlier statement said: “Passengers have the right to seek compensation under EU legislation when flights are delayed by three hours or more, cancelled or when they are denied boarding.
“We note that the recent industrial action is not by Ryanair’s UK employees, but it is the view of the UK Civil Aviation Authority, taking account of previous Court rulings, that when a flight cancellation is caused by strike action by the airline’s employees, the airline is required to pay compensation to passengers in respect of the cancellation of the flight, if it has not warned passengers of the cancellation at least two weeks prior to the scheduled time of departure.
“In the case of the most recent industrial action involving Ryanair, passengers must first submit their claim to the airline and if they are not satisfied with the response, they can seek redress via the approved Alternative Dispute Resolution service.”
