MONTREAL (Reuters) - Air Canada said on Tuesday it is seeking to appeal to the country’s highest court a decision last year ordering the airline to keep heavy maintenance operations in Montreal.

In November, the Quebec Court of Appeal ruled against the country’s largest carrier, upholding a lower court’s 2013 decision that Air Canada must keep the operations in Montreal.

“We are seeking to appeal to the Supreme Court of Canada the Quebec Court of Appeal’s decision in order to provide clarity on important issues it raises,” Air Canada spokeswoman Isabelle Arthur wrote in an email. “As this is before the court, we have nothing to add to our filing.”

The government of the predominantly French-speaking province argued that Air Canada breached its legal obligations to keep heavy maintenance operations in the country after the carrier closed a facility in Montreal in 2012.

The facility was operated by the former Aveos Fleet Performance, once an important Air Canada contractor. In 2012 Aveos obtained creditor protection and laid off its 2,600 Canadian employees, including about 1,700 workers in Montreal.

The Air Canada Public Participation Act, the law that has governed Air Canada’s operations since its 1988 privatization, says the airline must maintain overhaul centers in Quebec, Manitoba and Ontario.

The appeals court said Air Canada was contravening the act by not maintaining an aircraft overhaul operations in Montreal.

Air Canada declined to comment further on Tuesday.

The airline has previously said it is compliant with the act and does maintenance in Montreal, Winnipeg, Toronto, Vancouver and other cities. In 2013, Air Canada signed a five-year agreement with a heavy maintenance facility in Trois-Rivieres, Quebec for the carrier’s fleet of Embraer E-190 and E175 aircraft.

Air Canada also sends work to heavy maintenance centers in the United States, including facilities run by AAR Corp in Minnesota.

On Monday night, the union representing the former Aveos workers said in a release that Air Canada sought leave to appeal to the Supreme Court on Dec. 30.

David Chartrand, Quebec coordinator for the International Association of Machinists and Aerospace Workers, said in the release that he is disappointed by the prospect of further legal action.

“In stretching the legal battle to the maximum, Air Canada tries to give itself opportunity to plead their own turpitude and make the return of these jobs as complex and difficult as possible.”