Ryanair has confirmed it will publish the full list of flight cancellations it expects before October 31st later.

The low-cost carrier has been coming under increasing pressure following news it would cancel as many as 50 flights a day over the coming weeks as it battles to accommodate pilot holidays.

The planned cancellations have been allocated, where possible, to Ryanair’s bigger base airports, and routes with multiple daily frequencies.

This will, Ryanair hopes, allow it to offer disrupted customers the maximum number of alternate flights and routes in order to minimise inconvenience.

Customers affected by these cancellations will be emailed with offers of alternative flights or full refunds, and details of their EU261 compensation entitlement, the carrier said.

Flights from Barcelona, Brussels South Charleroi Airport, Dublin, Lisbon, London Stansted, Madrid, Milan Bergamo, Porto, and Rome Fiumicino are expected to be hardest hit.

Ryanair chief executive Michael O’Leary said: “While over 98 per cent of our customers will not be affected by these cancellations over the next six weeks, we apologise unreservedly to those customers whose travel will be disrupted, and assure them that we have done our utmost to try to ensure that we can re-accommodate most of them on alternative flights on the same or next day.

“Ryanair is not short of pilots – we were able to fully crew our peak summer schedule in June, July and August – but we have messed up the allocation of annual leave to pilots in September and October because we are trying to allocate a full year’s leave into a nine month period from April to December.

“This issue will not recur in 2018 as Ryanair goes back onto a 12 month calendar leave year from 1st January 1st to December 31st 2018.

“This is a mess of our own making.

“I apologise sincerely to all our customers for any worry or concern this has caused them over the past weekend.

“We have only taken this decision to cancel this small proportion of our 2,500 daily flights so that we can provide extra standby cover and protect the punctuality of the 98 per cent of flights that will be unaffected by these cancellations.”

As many as 400,000 passengers could be affected by the cancellations.