Updated

Canada's labor minister said Wednesday the government will introduce legislation if necessary to end a strike at Canadian Pacific railway, which has forced the suspension of its freight service in Canada and the United States.

Teamsters Canada said the strike against Canada's second-largest railway started just after midnight Wednesday. The nation's larger railway, CN, can make up for some — but not all — of the transport needs.

The strike is expected to halt shipments of grain, fertilizer, coal, cars and other goods that Canadian Pacific moves along nearly 14,900 miles (24,000 kilometers) of track in Canada and the U.S.

"We received a mandate to protect the Canadian economy so that's why this morning I've already put on notice a bill to ensure that we are in a position to introduce legislation if necessary," Labor Minister Lisa Raitt said in Ottawa.

"We are going to continue to closely monitor the situation. The parties are at the table, they are negotiating but, at the same time, the strike goes on and productivity isn't happening in the country."

Raitt estimated that if the strike continues, it would cost the Canadian economy $540 million a week.

Raitt urged the parties to reach an agreement without government intervention. She said the parties are "very close."

Parliament would have to be recalled to pass back-to-work legislation. Raitt didn't give a specific date but suggested it could happen soon, perhaps Monday.

Prime Minister Stephen Harper's Conservative government has cited potential economic damage in the past for preventing or ending strikes at Air Canada and Canada Post.

Raitt said the government would prefer a negotiated settlement, and she'll make herself available for support. She also said that CN could take over some of Canadian Pacific's business.

"We believe a deal at the table is the best deal that can happen," she said. "Remember Canadian Pacific is a purely private company. We also have a larger railway, CN, that's able to provide service in the country. We want to make sure that the parties have some room to freely collective bargain."

Raitt noted previous governments in Canada have intervened in 10 prior work stoppages in the railroads.

The Mining Association of Canada expressed "grave concern" about the economic impact and urged the government to take immediate action to resolve the labor dispute. In a statement, the association called the strike a threat to the country's natural resources sector.

Both the Teamsters Canada union and Canadian Pacific spokesman Ed Greenberg have said negotiations will continue Wednesday. The union represents about 5,000 Canadian Pacific workers.

Union Vice President Doug Finnson said in a statement that major points of contention are pensions, some work rules and fatigue management.

Commuter trains in Montreal, Vancouver and Toronto continued to run Wednesday.

The strike comes amid big changes at the railway. Last week, Canadian Pacific appointed an interim chief executive after its chief executive, Fred Green, announced his departure, ending a months-long battle that pitted New York activist investor Bill Ackman against a board of directors stocked with Canadian business titans.

The railroad operator also elected a new board of 16 directors, including seven backed by Ackman, whose Pershing Square Capital Management fund is Canadian Pacific's largest shareholder with about 14 percent of the company's stock.