Ryanair says it intends to cancel 40 to 50 flights a day over the next six weeks because its staff need to catch up on holiday entitlement.

The airline angered passengers by cancelling more than 160 flights across Europe without notice or explanation on Friday.

A total of 82 flights were cancelled on Friday with 80 scheduled to be cancelled on Saturday.

Scores of passengers deluged the Ryanair Twitter handle on Friday seeking an explanation for the cancellations. Ryanair only responded by stating that it was as a result of “circumstances outside our control”.

Eventually Ryanair issued a statement on Friday evening saying that it needed to cancel the flights to “improve its system-wide punctuality which has fallen below 80 per cent in the first two weeks of September through a combination of air traffic control capacity delays and strikes, weather disruptions and the impact of increased holiday allocations to pilots and cabin crew as the airline moves to allocate annual leave during a 9 month transition period (April to December 2017) to move the airline’s holiday year (currently April to March) to a calendar year (Jan to Dec) from 1st January 2018 onwards”.

Ryanair spokesman Robin Kiely said the cancellations amounted to two per cent of the airline’s 2,500 flights and the goal will be to restore its on-time performance to its 90 per cent average.

He added: “Ryanair apologises sincerely for the inconvenience caused to customers by these cancellations. Customers will be contacted directly about this small number of cancellations and offered alternative flights or full refunds.”

Among the cancellations were 17 flights in and out of Dublin Airport . Departures to Tours and Newcastle on Friday and two flights to Barcelona, and one each to Madrid, Amsterdam, Edinburgh and London Gatwick on Saturday have been cancelled.

Arrivals from Rome, Tours, Newcastle and Paris Beauvais on Friday and flights on Saturday from Barcelona, Madrid, Exeter and two to Amsterdam have also been cancelled.

Angry passengers complained that no explanation was forthcoming from Ryanair about the cancellations on Friday.

One tweeted the airline: ”#ryanaircancellations unacceptable to state cancellations due to issues outside of your control without giving an actual reason.”

Another, whose flight from Manchester to Krakow was cancelled on Monday, tweeted: ”I’ve just an email saying my flight home on Monday is cancelled. Can you help please?”

Another wrote: ”My flight from Stansted to Pisa tomorrow has been cacnelled. Still showing up as scheduled elsewhere. What’s going on?”

A fourth tweeted: “I want to rebook my flight that you’ve cancelled from Bologna and can’t reach your customer service live chat. Can you help?”

Friday and Saturday cancellations

FR6341 Barcelona to El Prat Rome Fuimincino

FR4338 Bologna to Brindisi

FR9092 Trapani (Sicily) to Milan (Bergamo)

FR3005 Rome Ciampino to London Stansted

FR7422 Stockholm to Alicante

FR4601 Bologna to Malaga T2

FR4100 Frankfurt Main to Malaga T2

FR4111 Milan (Bergamo) to Capodichino

FR4709 Alghero to Milan (Bergamo)

FR1382 Charleroi to Zaragosa

FR9428 Dublin T1 to Milan (Bergamo)

FR876 London Stansted to Beziers

FR7542 Manchester to Barcelona El Prat

FR4007 Manchester to Alicante

FR2225 London Stansted to Tallinn

FR5041 Leeds Bradford to Bratislava

FR9432 Dublin T1 to Rome Ciampino

FR9135 Porto to Paris Beauvais

FR9366 Barcelona El Prat to Bologna

FR8882 Edinburgh to London Stansted

FR3048 Porto to Krakow

FR4339 Brindisi to Bologna

FR6342 Rome Fuimincino to Barcelona El Prat

FR9091 Milan (Bergamo) to Trapani (Sicily)

FR4112 Capodichino to Milan (Bergamo)

FR4708 Milan (Bergamo) to Alghero

FR1383 Zaragosa to Charleroi

FR877 Beziers to London Stansted

FR3002 London Stansted to Rome Ciampino

FR8881 London Stansted to Edinburgh

FR9429 Milan (Bergamo) to Dublin T1

FR8816 London Stansted to Nimes

FR1782 London Stansted to Bordeaux

FR4602 Malaga T2 to Bologna

FR9367 Bologna to Barcelona El Prat

FR7543 Barcelona El Prat to Manchester

FR9134 Paris Beauvais to Porto

FR3484 Bologna Palma to Mallorca

FR5042 Bratislava to Leeds Bradford

FR9927 Alghero to Pisa

FR5505 Milan (Bergamo) to Nuremberg

FR8631 Trapani (Sicily) to Charleroi

FR4110 Malaga T2 to Frankfurt Main

FR2224 Tallinn to London Stansted

FR4006 Alicante to Manchester

FR7423 Alicante to Stockholm

FR9111 Barcelona El Prat to Turin

FR9431 Rome Ciampino to Dublin T1

FR8884 Edinburgh to London Stansted

FR3047 Krakow to Porto

FR9928 Pisa to Alghero

FR1783 Bordeaux to London Stansted

FR5506 Nuremberg to Milan (Bergamo)

FR8817 Nimes to London Stansted

FR3485 Palma Mallorca to Bologna

FR9112 Turin to Barcelona El Prat

FR8883 London Stansted to Edinburgh

FR8632 Charleroi to Trapani (Sicily)

FR2993 Dublin T1 to Tours

FR72 London Stansted to Carcassonne

FR7382 London Stansted to Copenhagen

FR8082 Fez to Charleroi

FR1062 Madrid to Modlin Warsaw

FR2994 Tours to Dublin T1

FR7233 Vilniaus to Paris Beauvais

FR6212 Dusseldorf Weeze to Alicante

FR2528 Madrid to Berlin

FR2945 Porto to Berlin

FR73 Carcassonne to London Stansted

FR7381 Copenhagen to London Stansted

FR9848 Pisa to Chania (Crete)

FR58 London Stansted to Stockholm

FR8081 Charleroi to Fez

FR7234 Paris Beauvais to Vilniaus

FR6213 Alicante to Dusseldorf Weeze

FR1063 Modlin Warsaw to Madrid

FR2529 Berlin to Madrid

FR9849 Chania (Crete) to Pisa

FR2946 Berlin to Porto

FR174 Dublin T1 to Newcastle

FR59 Stockholm to London Stansted

FR175 Newcastle to Dublin T1