Ryanair is making life tougher for passengers who choose not to pay extra for assigned seating.

The airline, which is Europe’s biggest no-frills carrier, has told passengers paying only the basic fare that, from next month, the window for checking in online for free is shrinking from a week to four days.

The move will infuriate passengers who are happy to have their seats allocated randomly, avoiding the charge. At present anyone who is on holiday for a week can check in and print out boarding passes for both legs – or download them to the Ryanair app – on the day of departure.

From next month, such travellers will need to interrupt their holidays to find a computer on which to check in and print out their boarding passes, or find some wifi to use the Ryanair app (though some airports in Greece and Morocco cannot handle smartphones at check-in).

Alternatively, travellers can opt to pay £6 per person, per flight for assigned seating. That allows check-in up to one month ahead of departure.

Ryanair’s email to passengers said: “From 1st November, free online check-in will be available from 4 days to 2 hours ahead of departure. Customers who do not wish to reserve their preferred seat, can check-in online or on the mobile app free of charge between 4 days and 2 hours before departure and will be allocated a random seat.”

It goes on to point out that anyone who has booked a seat “can check-in online and on the app, from between 30 days and 2 hours before their flight”.

The change applies to existing reservations as well as new bookings. The airline said: “Affected customers who do not wish to accept this policy change have the right to cancel and request a refund,” providing they do so within five days.

A Ryanair spokesperson told The Independent the move was in response to “extensive customer feedback” and was intended “to increase the choice available to customers who wish to reserve their seat onboard”.

Passengers responded swiftly to the news. Peter Lilley tweeted: “I trust @Ryanair isn't returning to its old ways of thinking it doesn’t matter how you treat customers?”

But Brian Watkinson tweeted: “With BA, Air France etc you can only check in 24 hours ahead. So no big deal really.”

Ryanair's slogan is “Always Getting Better”.