Ryanair is breaking the law in its handling of flight cancellations, the boss of the UK's aviation regulator has claimed.
Andrew Haines, chief executive of the Civil Aviation Authority (CAA), said he was "furious" with the Dublin-based carrier because it is not telling passengers they are entitled to be re-routed by other airlines.
"They are not making it clear to people their entitlement," Mr Haines told BBC Radio 4's Today programme.
"If they follow through on what they are saying then they would be breaking the law."
A Ryanair spokesman said: "We will be meeting with the CAA and will comply fully with whatever requirements they ask us to."
On Wednesday the airline cancelled an extra 18,000 flights for the winter season in a move that will hit 400,000 customers.
Ryanair is facing a multi-million compensation bill for cancelled flights after it previously revealed it was shelving up to 50 flights a day up to the end of October.
It says the cancellations were brought about because of an error with pilot holiday rosters.