Prime Minister Justin Trudeau has congratulated U.S. President Trump on his inauguration.

The Prime Minister's Office says the two men spoke by phone Saturday, but it was not immediately clear how long the conversation lasted.

The PMO said in an email that Trudeau noted the depth of the Canada-U.S. economic relationship, with 35 states having Canada as their top export market.

The PMO email also said the two men reiterated the importance of the relationship between the two countries.

The two men also spoke in November after Trump's stunning election victory and Trudeau invited the then-president-elect to visit Canada at the earliest opportunity.

Saturday's email said the two men "looked forward to meeting soon."

'A constructive conversation'

Trump's spokesman Sean Spicer said "the president had a constructive conversation with Prime Minister Trudeau of Canada about strengthening the relationship between our two nations."

"They also discussed setting up additional meetings in the days to come, which we will follow up on," Spicer said.

Some of Trudeau's top advisers have met with Trump's camp in the weeks heading up to Friday's inauguration as Canadian officials have been concerned about what impact Trump's plans for the U.S. economy would have on Canada.

Among other things Trump has vowed to renegotiate the North American Free Trade Agreement and Spicer recently suggested Canada's automotive sector might not be spared from a border tax. Trump has also threatened to impose tariffs on foreign vehicles built in Mexico.

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Trudeau's office said Friday that he has talked to the premiers about the new American administration and the opportunities presented by the transition in Washington.

He also urged the mayors of Canada's biggest cities to keep close ties with their U.S. counterparts, saying those relationships will be vital to ensuring open dialogue and trade.