The Civil Aviation Authority today revealed that has started enforcement action against the Irish no-frills carrier.

The UK aviation regulator has stepped in amid concerns over compensation due to passengers disrupted by summer strike action at the carrier.

This follows the airline’s decision that financial compensation is not payable under European Commission Regulation 261/2004 for flight disruption resulting from industrial action by the airline’s staff this summer.

“Ryanair passengers have made claims for compensation directly to the airline, but these have been rejected,” the CAA said.

“Passengers have then been able to escalate their complaints to AviationADR, a body approved by the Civil Aviation Authority, to provide alternative dispute resolution for passenger complaints.

“Ryanair has now informed the Civil Aviation Authority that it has terminated its agreement with AviationADR.

“As the Civil Aviation Authority said at the time of the industrial action, in its view, the strikes were not ‘extraordinary circumstances’ and were not exempt, meaning consumers should be compensated in accordance with Regulation EC261/2004.

“As a result of Ryanair’s action, passengers with an existing claim will now have to await the outcome of the Civil Aviation Authority’s enforcement action.”

The action means that the airline could be face a UK legal proceedings under the Enterprise Act.

More Ryanair passengers have put in compensation claims for cancellations or delays to arbitration this year than any other airline. Figures from the Alternative Dispute Resolution (ADR) service showed the airline accounted for the largest proportion – 30% – of all appeals.

Ryanair said: “Courts in Germany, Spain and Italy have already ruled that strikes are an ‘exceptional circumstance’ and EU261 compensation does not apply.

“We expect the UK CAA and courts will follow this precedent.”

But Rory Boland, travel editor at consumer group Which?, 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.”