US President Donald Trump threatened on Monday to stop the opening of a new bridge between the United States and Canada, in a fresh salvo against the country he has suggested should become the 51st US state.

Trump said the United States should own "at least half" of the still under-construction Gordie Howe International Bridge that links the Canadian province of Ontario with the US state of Michigan.

Work on the US$4.7 billion bridge – named after the late Canadian-born National Hockey League great Gordie Howe – started in 2018 and it is due to open later this year.

"I will not allow this bridge to open until the United States is fully compensated for everything we have given them, and also, importantly, Canada treats the United States with the Fairness and Respect that we deserve," Trump posted on Truth Social.

"We will start negotiations, IMMEDIATELY."

The 79-year-old Republican complained that Canada owned both sides of the bridge and used "virtually" no US products to build it.

"And now, on top of everything else, Prime Minister (Mark) Carney wants to make a deal with China – which will eat Canada alive. We'll just get the leftovers! I don't think so," Trump added.

Washington has threatened to slap 100 percent tariffs on Canada after Carney visited Beijing last month and sealed a preliminary trade deal with China.

The US leader meanwhile repeated the outlandish claim that Beijing would "terminate ALL Ice Hockey being played in Canada."

Trump has clashed with Canada over trade since returning to office in January 2025. He previously called for the United States to annex Canada but has largely dropped that claim in recent months.

Carney meanwhile warned at the Davos forum last month that the US-led global system of governance is enduring "a rupture," in a thinly veiled reference to Trump's disruption, and argued for mid-level powers to group together. (AFP)