Canadian Prime Minister Justin Trudeau said Thursday that his country's border with the United States would not fully reopen for at least several weeks, rejecting US President Donald's Trump overtures to do so sooner.

The border - the world's longest international frontier at 8,900 kilometres - was shut to all non-essential travellers on both sides on March 21 in response to the coronavirus crisis. Cross-border trade has continued.

"We are having ongoing discussions on border issues, on supply chains with the United States all the time," Trudeau told reporters at his daily briefing.

But "the reality is that it will still be many weeks" before "we can talk about relaxing the restrictions on our borders," he said.

We "must protect our citizens, as every country does," Trudeau added. "Most countries in the world have restricted travel, and Canada and the United States are no exception."

Trudeau's deputy and point person on US relations, Chrystia Freeland, added that Ottawa will only ease border restrictions "when it is not a risk to the health and safety of Canadians."

Canada's population is about nine times smaller than that of the United States. So far, the US has recorded more than 30,000 coronavirus deaths, while Canada's death toll is roughly 1,200.

But the two Canadian provinces most affected, Quebec and Ontario, border New York state - the epicenter of the US outbreak.

Some Can$2.4 billion (€1.6 billion) worth of goods and more than 400,000 people crossed the border each day on average, prior to the pandemic.

Trump had said on Wednesday that the border with Canada would be "one of the early borders to be released."

"Our relationship with Canada is very good -- we'll talk about that," the US leader said. "Canada's doing well, we're doing well -- so we'll see, but at some point, we will be doing that."

Trump said the US would be "keeping very strong borders" with nations that had high infection rates.