Hours after the union gave notice that it intends to strike at one minute after midnight on Sunday night, Raitt said that a work stoppage is "not in the best interests of the Canadian public or Canadian businesses".

"The government of Canada is committed to doing what it takes to protect the public interest and help unions and employers achieve constructive labor relations," she said in an emailed statement to Reuters.

A strike would come at an awkward time for Air Canada as next week is spring break for schools in many parts of Canada and March is generally a busy flying month.

The Conservative federal government has not been shy to step in quickly to block strikes or end them quickly at Air Canada as well as Canada Post, either by legislation or other means.

The International Association of Machinists and Aerospace Workers informed Air Canada on Tuesday that it plans to strike. The union represents about 8,600 mechanics, baggage handlers and cargo agents.

The action comes after the union's membership voted against a tentative four-year contract deal that the union had negotiated with Air Canada.

"The lines of communication remain open and we are hopeful that there remains sufficient time to avoid a work disruption," Duncan Dee, Air Canada's chief operating officer, said in a statement.

If a settlement is not reached and the union goes ahead with the strike, the airline said it will work to minimize inconvenience to its passengers.

"I encourage both parties to continue bargaining and reach a new collective agreement as soon as possible," Raitt said. "The government is concerned that a strike is possible and is taking this situation very seriously."

Raitt's statement did not say if she would pass back-to-work legislation to prevent a strike, but added: "Canadians gave our government a strong mandate to protect the economic recovery and create jobs."

Air Canada's stock was down 2 percent at 95 Canadian cents in early trade on the Toronto Stock Exchange on Wednesday.

(Reporting by Randall Palmer in Ottawa and Nicole Mordant in Vancouver; Editing by Janet Guttsman and Peter Galloway)

• A Permanent Economic Emergency