The carrier said there had been “a significant increase in sick leave” at the airline and its partners. 

Ole Orver, Finnair chief commercial officer, said: “Staff sick leave is now significantly impacting Finnair and airports in Finland as well as throughout the world. 

“We aim to meet these resourcing challenges through the cancellation of flights, to avoid last-minute changes and better manage our customers’ expectations. This will give customers more time to prepare for flight schedule changes and adjust their travel plans if needed.”

Most cancellations are on routes where Finnair operates multiple daily flights, with customers offered an alternative flight to the same destination on the same day. 

Changes will also be made to long-haul flights; the inaugural Dallas service will move from February to 27 March, while the start of a Nagoya service and added frequencies to Osaka are postponed to the summer season. 

"We are sorry for the inconvenience and disruption this may cause to our customers. However, reducing our traffic programme is necessary to better offer a smooth travel experience in the face of the expected resource challenges,” said Orver.

Finnair will also reduce weekly frequencies to Singapore to twice a week and Hong Kong to three. It said it would email customers affected by cancellations “and do its best to find alternative flights for them”. 

Customers with cancelled flights also have the option to apply for a refund for unused tickets. 

Further disruption is possible on Monday (17 January), when labour union Pro may cause flight cancellations.