At least 200,000 customers could be affected by the stand-off between Ryanair and passengers whose travel plans were hit by strikes.

The UK Civil Aviation Authority today started enforcement action against the airline following its decision not to pay compensation for disruption resulting from industrial action by its staff in the summer.

The CAA said Ryanair passengers have made claims for compensation directly to Ryanair, but these claims have been rejected.

Passengers then escalated their complaints to AviationADR, a body approved by the CAA to provide alternative dispute resolution for passenger complaints. But Ryanair has now informed the CAA it has terminated its agreement with AviationADR.

In a statement, the CAA said its view continues to be that industrial action does not represent ‘extraordinary circumstances’, the exemption set out in EU regulations, and customers should therefore receive compensation where their flight was delayed by more than three hours as a result.

Passengers with an outstanding claim will now have to await the outcome of the CAA’s enforcement action through the courts. Lawyers from north west firm Bott and Co, which has its own flight delay department, have told the Gazette that more than 200,000 people could have been affected by cancellations and delays in the summer. Taking into account the average payment made to delayed customers, this could cost the company as much as £55m.

Rory Boland, travel editor of Which?, said Ryanair had attempted to ‘shirk its responsibilities’ by refusing to pay out compensation for cancelling services during the summer. ‘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.’

In a statement today, a Ryanair spokesperson 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.’

Coby Benson, flight delay compensation solicitor from Bott and Co, said decisions taken in other jurisdictions are not legally binding on the English courts.

'The reasoning within the Spanish judgment does not stand up to scrutiny and would certainly be appealable in the English legal system,' he said. 'Crucially the decisions do not appear to have taken into account a recent European court ruling which held that strikes caused by disagreements over working conditions are not extraordinary circumstances since they are both within the airline’s control and also an inherent part of running a business.'