An acute shortage of pilots was the cause behind the airline’s forced cancellations, reports newspaper Dagens Næringsliv.

Thousands of passengers in Norway and other countries have been left stranded or forced to cancel travel plans due to the cancellations.

Several flights have been cancelled over the last few days, including services to and from Denmark, where a flight between Aalborg and Copenhagen was cancelled Tuesday morning.

But Norwegian moved to reassure passengers on Tuesday.

“We currently have no cancellations, and it looks as though we will now operate in accordance with the schedule,” the company’s information officer Daniel Kirchhoff told Danish broadcaster DR.

Danish passengers were stranded in Budapest Monday, when three Aalborg-Copenhagen flights were also cancelled.

Norwegian scheduled replacement bus services in place of the domestic flights.

Flights from Copenhagen to Oslo, Stockholm and Paris were also cancelled.

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The disruption to the budget airline’s services was blamed on an acute shortage of pilots, even though the airline offered its pilots quadruple pay to work during their holidays, reports Dagens Næringsliv.

The offer was rejected by the Norwegian Pilot Union (NPU).

“Maybe some pilots would say yes to working even though they were tired. And this job requires us to be alert all of the time,” NPU chief Halvor Vatbar told Dagens Næringsliv.

Kirchhoff confirmed that the pilot shortage was behind the cancellations.

“We have been short of pilots, and that is deeply regrettable. We always try to plan as well as possible and look into all options for bringing in extra pilots,” he said to DR.

“We understand that it is extremely frustrating for passengers,” he said.

The company’s director of flights Tomas Hesthammer told Norwegian newspaper VG that the lack of pilots available in the Scandinavian country represented a “fundamental problem”.

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“We are working full time to find short-term solutions, such as hiring manned aircraft from other operators to serve the routes we cannot cover ourselves. But it is very difficult during the peak season,” he said.

Kirchhoff told DR that passengers should contact Norwegian via its website for information on compensation.