LAUSANNE, Switzerland — Norwegian cross-country skier Martin Johnsrud Sundby is losing his 2015 overall World Cup and Tour de Ski titles over a doping infringement.

The Court of Arbitration for Sport said Wednesday it has suspended Johnsrud Sundby for two months as it upheld an appeal by WADA against the FIS Doping Panel, which had initially cleared the 2014 Olympic bronze medallist of wrongdoing.

According to the International Ski Federation, Dario Cologna of Switzerland takes over the 2014-15 overall championship title, and Petter Northug of Norway has been awarded the 2015 Tour de Ski title. Johnsrud Sundby still holds the overall titles for 2013-14 and 2015-16.

In a statement released by the Norwegian ski federation, Johnsrud Sundby said his situation is "an athlete's worst nightmare."

"I have always competed on clean and honest terms," he said. "I hope and believe that this case will not have major consequences for my further career, nor for the preparations of the upcoming season."

Johnsrud Sundby failed two tests for salbutamol, a medication he used to treat asthma. The tests took place during World Cup events in Davos, Switzerland, in December 2014 and in Toblach, Italy, the following month.

While the medication is normally applied by a handheld metric dose inhaler, Johnsrud Sundby used a nebulizer and exceeded the allowed maximum dose of salbutamol. The doping panel of FIS ruled the athlete didn't breach anti-doping rules and refrained from further action.

Following the appeal by the World Anti-Doping Agency, CAS overturned the decision as Johnsrud Sundby had not obtained an exemption to use a higher dose. As a consequence, Johnsrud Sundby's results in the Davos and Toblach events have been disqualified.

However, CAS handed him a suspension shorter than usual as "there was medical justification for the athlete's use of salbutamol" and "that his degree of fault was light." The ban started on July 11.

"The CAS award is difficult to understand," Johnsrud Sundby said. "CAS finds the rule to be unclear and the degree of fault is light. Still I am severely punished. I have always been careful with my medication and followed the (Norwegian ski federation's) regulations and the doctor's recommendations exactly ... I had no reason to doubt their understanding of the regulations."

The Norwegian federation said it assumed full responsibility for the matter, adding it would compensate Johnsrud Sundby for the prize money of around $130,000 which he loses.

In a statement, FIS said it "fully shares the view of the CAS that Martin Johnsrud Sundby is not to be considered as an intentional doping offender" and that the sanctions result from "his reliance on questionable medical advice to administer salbutamol outside a hospital."

A winner of 24 World Cup races, Johnsrud Sundby finished third in the 30-kilometre skiathlon at the Sochi Games and won silver with the Norwegian team in the 4x10K relay at the Vancouver Olympics in 2010.