Budget airline Ryanair is cancelling 40 to 50 flights every day for the next six weeks in a bid to improve its punctuality, but many passengers have been left stranded after being given “no notice” about the cancellations.

The Irish-based airline said strikes in Europe, air traffic control issues and bad weather had caused its punctuality level to drop to “unacceptable” levels, and that it also had a backlog of staff leave to clear by the end of the year.

“Ryanair’s on-time performance has declined from 90 per cent to under 80 per cent over the past two weeks, a figure that is unacceptable to Ryanair and its customers,” the airline said in a statement.

The cancellations could affect up to 400,000 passengers, who will be offered alternative flights or refunds.

The airline cancelled 80 flights on Saturday and 82 on Sunday, leaving many passengers stranded when they were told via text message that their flights had been scrapped.

“We got no notice and have to stay an extra three days in Rome with no help or support from Ryanair,” one Twitter user said.

“We’re out 400 euro ($600) already and we still have to get to Monday before the next available flight. It’s madness. I’ll never fly Ryanair again.”

Another Twitter user said they found out their flight was cancelled by checking the website on the morning of their flight.

“We’re due to fly at 10am and still haven’t received an email and it’s on the website the flight is cancelled! Never fly with them again,” the user wrote at 7am.

Customers call for full list of cancelled flights

Ryanair published the weekend’s cancellations online but has not publicly confirmed which other flights will be axed over the next six weeks, causing angst for many customers who have booked travel with the airline.

The airline told customers flights would operate as scheduled, unless passengers received a cancellation email.

“Release a list of flights with more than 24 hours’ notice please, so people can actually arrange alternative ways to travel,” one Twitter user said.

“Publishing the cancelled flights for the next two days … why not publish them all? Shambles of a company,” said another.

Ryanair said it apologises “sincerely to the small number of customers affected by these cancellations” and would work to organise alternative flights and/or full refunds.

“Cancellation notices for flights cancelled up to and including Wednesday September 20 have been sent to affected customers and we will continue to send regular updates and post flight information on our website,” the airline said on Facebook.

“We have messed up in the planning of pilot holidays and we’re working hard to fix that.”

The airline said that less than 2 per cent of its flights would be cancelled.

This must be some joke? 3 days notice a joke! You are gonna lose so much custom. This is totally unacceptable! CAA should revoke licence

— DJ Nerja 🇪🇦 (@CurryInTurry) September 15, 2017

https://twitter.com/DaleofEurope/status/909097345215815680

2% of your customers' travel plans are in ruins. Due to lack of info, the other 98% are terrified! Well done Micko, best PR ever!

— Paul Waldron (@majorvonwaldron) September 16, 2017

–ABC