Canadian Pacific Railway Ltd. trains were halted Sunday morning, stalling global shipments of key manufactured goods and commodities such as fertilizers, after an impasse in contract negotiations between the company and its conductors and engineers.

The Teamsters Canada Rail Conference, which represents more than 3,000 conductors, engineers and yard workers at Canadian Pacific, issued a statement near midnight Sunday Eastern time stating that the railway initiated the lockout after the union failed to meet the company’s deadline for approving a new contract.

Patrick Waldron, a spokesman for Canadian Pacific, said the union misrepresented the cause of the work stoppage. The railway’s representatives were still at the negotiating table with a federally appointed mediator in Calgary, Alberta, waiting for a response to a new contract offer when the union issued its statement that the railway had initiated a lockdown.

“The actions of the teamsters’ leadership last night were dishonest and irresponsible. The union falsely claimed that Canadian Pacific initiated a lockout. In fact it was the union that initiated the work stoppage,” Mr. Waldron said.

Canadian Pacific continues to want to bargain in good faith with the union, he said. “The union’s actions show a complete disregard for the unnecessary damage this will cause to the supply chain,” Mr. Waldron said.

The union didn’t immediately respond to a request for comment.

The railway has been in negotiations and mediation since September with the union, which seeks increased wage and pension benefits and more rest times. The situation marks the fourth time since 2011 that the contract negotiations with the Teamsters triggered work stoppages at Canadian Pacific.

The prospect of a strike prompted a number of businesses, customers and politicians to publicly urge the Canadian government to introduce back-to-work legislation that would force striking workers to return to their jobs. Such a law would require a vote of Canada’s parliament, which is set to convene Monday after a break.

Canada’s labor minister, Seamus O’Regan,

traveled to Calgary, Alberta, where contract negotiations are taking place. He had urged both sides to avoid a work stoppage that would exacerbate existing supply-chain bottlenecks and rising commodity prices. Halting Canadian Pacific’s trains “could not have come at a worse time,” he said in a video statement posted on Twitter.

Canadian Pacific is the sixth-largest freight railway in North America, shipping goods across Canada and south to central U.S. states. It is the primary shipper of fertilizers such as Canadian potash, which is mined in the province of Saskatchewan.

Nutrien Ltd. is the world’s largest corporate potash producer and most production from its Saskatchewan mines is transported by Canadian Pacific to ships destined for foreign nations. Nutrien said this week that it plans to increase its annual production of potash this year by about 7%, or nearly 1 million metric tons, after potash shipments from Russia and Belarus, major producers, were effectively halted in the wake of the Ukraine war.

Nutrien Chief Executive Ken Seitz

said that if the rail strike extends for more than a few weeks, the company will start reducing production at its potash mines because its warehouses are currently full of the fertilizer for planting season.

“It’s a frustrating situation given what is going on in the world, and we would expect some legislation,” he said.

Write to Jacquie McNish at Jacquie.McNish@wsj.com