By Paul Vieira

OTTAWA — Canada will provide billions of dollars to help upgrade infrastructure and clear congestion at the country's biggest port in Vancouver, British Columbia, Prime Minister Mark Carney said Thursday.

The money is meant to address warnings that constraints at Canada's ports posed a sizable hurdle in the Carney-led Liberal government efforts to reduce dependence on crossborder trade with the U.S. to drive growth.

Carney said his government would provide the equivalent of $7 billion to expand capacity at the Vancouver Fraser Port Authority. At a press conference in the Pacific Coast city, he said the infrastructure upgrades would help unlock over $70 billion in new trade capacity and add over $2 billion in output.

Carney said the $7 billion figure, or 10 billion in Canadian dollars, is not an estimate of what the government intends to provide, and not a final total. More details on the Vancouver port's expansion would be forthcoming, he said.

Carney, and analysts at the Bank of Canada, had warned this year that the country had fallen behind on upgrading the infrastructure at its marine ports.

"Canadian ports became relatively less central in global shipping networks compared with what they once were," the central bank's analysis said, noting that Canadian ports can't accommodate some of the latest, ultra-large container ships being deployed.

In testimony before lawmakers in May, Bank of Canada Gov. Tiff Macklem said some goods originating from China and destined for Canada are loaded onto these big vessels, and have to dock in Los Angeles. Once in California, the Canadian-bound goods get slapped with Trump administration tariffs.

"So things from China are more expensive in Canada, even though we did not impose new tariffs," Macklem said.

The port of Vancouver handles roughly $700 million in commerce each day, and more cargo than the next five largest Canadian ports combined.

The port's success "is now straining capacity and bottlenecks are worsening," Carney said. "Ships wait to load their cargo. It takes too long to get imported goods to Canadians. That slows our trade, loses new business to the U.S., increases prices here at home, and holds our economy back."

The billions for Vancouver's port was part of a broader agreement, between Ottawa and British Columbia, to deliver federal support for other projects — covering mining, electricity transmission and road infrastructure.

Write to Paul Vieira at paul.vieira@wsj.com