The Civil Aviation Authority has launched enforcement action against Ryanair after the firm refused to compensate passengers for flight disruptions during strikes over the summer.
The regulator said the widespread strikes were not “extraordinary circumstances” and were therefore not exempt, meaning Ryanair customers should be compensated.
In October the commercial court in Barcelona ruled that no compensation should be paid by Ryanair in the wake of strikes.
A Ryanair spokesman said: “Courts in Germany, Spain and Italy have already ruled that strikes are an extraordinary circumstance and EU261 compensation does not apply.
“We expect the UK CAA and courts will follow this precedent”
Ryanair’s flights were hit by widespread strikes over the summer by the carrier’s pilot and cabin crews, while it also suffered amid the industry-wide air traffic control industrial action that saw thousands of flights cancelled across Europe.
Rory Boland, editor of magazine Which? Travel, said: “Customers would have been outraged that Ryanair attempted to shirk its responsibilities by refusing to pay out compensation for cancelling services during the summer – which left hard-working families stranded with holiday plans stalled.
“It is right that the CAA is now taking legal action against Ryanair on the basis that such strikes were not extraordinary circumstances and should not be exempt, to ensure that the airline must finally do the right thing by its customers and pay the compensation owed.”
The CAA said passengers with an existing claim will now have to wait until the outcome of its enforcement action against the airline.
The watchdog has made repeated calls for Ryanair to compensate passengers affected by staff strikes.
Airlines can refuse to pay out for “extraordinary circumstances”, which normally involves bad weather or air traffic controller strikes.
Ryanair warned over profits in October after it was stung by strike action, combined with higher oil prices.
The carrier has seen the strike action knock passenger confidence in the company, revealing in October that passengers made fewer forward bookings into the third quarter, including for the October school half-term and Christmas.
Since the summer of severe disruption, Ryanair has been securing a series of agreements with unions across Europe over wages and benefits.
The latest was announced on Tuesday, with German pilots’ union VC.