By Allison Lampert

MONTREAL (Reuters) -The Canada Industrial Relations Board ordered on Saturday a halt to work stoppages at the country's largest railways, signaling an end to an unprecedented service disruption at both main freight rail carriers that threatened to hammer Canada's export-driven economy.

The independent labor tribunal made the decision after Canada asked it on Thursday to end an impasse in separate talks between more than 9,000 Teamsters members, and Canadian National Railway and Canadian Pacific Kansas City.

The Teamsters said in a statement that workers' rights were "significantly diminished" with the ruling and that it would appeal in federal court.

The board's decisions are the latest twist in the labor disputes at CN and CPKC, which locked out Teamsters members on Thursday, triggering a simultaneous rail stoppage that business groups said could inflict hundreds of millions of dollars in economic damage.

Canada, the world's second-largest country by area, relies heavily on trains to transport a wide range of commodities and goods.

Canadian Labour Minister Steven MacKinnon said on social media site X that he expects "railway companies and employees will resume operations at the earliest opportunity."

The decision will restart railway operations at CPKC where workers had been both locked out and on strike, by 00:01 ET (0401 GMT) on Monday, the railway said in a statement.

A Teamsters spokesperson said workers would not come back earlier, despite CPKC's request for employees to return on Sunday.

"We anticipate it will take several weeks for the railway network to fully recover from this work stoppage and a period of time beyond that for supply chains to stabilize," CPKC said.

The labor board's decision averted a planned strike on Monday by locomotive engineers, conductors and other workers at Montreal-based CN just days after Canada's largest railway ended a lockout and began restoring service. The Teamsters confirmed its CN workers would not strike on Monday after the CIRB decision.

Along with ordering an end to the stoppage, the board implemented government requests to impose binding arbitration on the parties to reach new deals and to impose a continuation of the existing contracts until new agreements are reached.

"This decision by the CIRB sets a dangerous precedent," said Paul Boucher, president of the Teamsters Canada Rail Conference. "It signals to corporate Canada that large companies need only stop their operations for a few hours, inflict short-term economic pain, and the federal government will step in to break a union."

A CN spokesperson said the company would have preferred a negotiated agreement, but "we are satisfied that this puts an end to the labor stoppage."

The disruption could have drastically affected farmers and agriculture companies in both Canada and the United States.

Wade Sobkowich, executive director of the Western Grain Elevator Association, which represents grain companies, said they had urged the government for weeks to refer the matter to the CIRB.

"It means that the government has really listened to what Canadians were telling them," he said. "We can't take a self-inflicted wound on the economy."

Mike Steenhoek, executive director of the U.S. Soy Transportation Coalition said the Canadian government had to intervene to help farmers who rely on seamless cross-border trade.

"We have not taken a side between railroads and railroad workers," Steenhoek said. "However, we are on the side of the American farmer."

On Thursday, MacKinnon, said his decision to refer the matter to the CIRB would survive a court challenge given his broad power under the country's labor code.

The Teamsters union wants its members' working conditions and pay to be determined by bargaining, despite disputes with CN and CP over scheduling, shift duration and availability. CN, for example, wants employees to work up to 12-hour shifts, compared with 10 hours in the current agreement, a move opposed by the union.

(Reporting By Allison Lampert in Montreal; Editing by Rod Nickel)