Donald Trump said he would press ahead with imposing tariffs of 25 per on all imports from Canada and Mexico from Tuesday, adding that there was “no room” for last-minute negotiation and prompting a market sell-off.

The US S&P 500 share index fell more than 2 per cent on the US president’s comments, and the tech-dominated Nasdaq Composite dropped more than 3 per cent.

Individual stocks fared worse, with chipmaker Nvidia plunging 9.6 per cent and energy group ConocoPhillips down 7.6 per cent.

Trump’s remarks came a day after his commerce secretary Howard Lutnick suggested that the extent and timing of the planned tariffs were still to be finalised, describing the situation as “fluid”.

But at the White House on Monday afternoon, Trump said: “The tariffs, you know, they’re all set. They go into effect tomorrow.”

The president’s plans to impose steep tariffs on major US trading partners have prompted concerns over their impact on the world’s largest economy.

Last month, Trump issued an executive order applying additional tariffs of 25 per cent to all imports from Canada and Mexico, with the exception of Canadian oil and energy products, which will face a 10 per cent levy.

Canada is by far the biggest foreign oil supplier to the US, accounting for about 60 per cent of its crude imports.

Days later, he postponed the implementation of the tariffs to March 4, following frantic last-minute diplomacy between Trump and Mexican President Claudia Sheinbaum and Canadian Prime Minister Justin Trudeau.

On Monday, Trump said that Canada and Mexico were “going to have a tariff”, suggesting that the measures would incentivise the two countries to move more of their manufacturing into the US.

“So what they have to do is build their car plants, frankly, and other things in the United States, in which case they have no tariffs,” he said.

Last week, Trump threatened to boost his additional tariffs on Chinese imports to 20 per cent beginning on Tuesday.

When asked on Monday what the maximum tariffs he would apply against Chinese imports would be, he replied: “I can’t say, it depends on what they do with their currency, it depends on what they do in terms of . . . some kind of an economic retaliation.”

Trump added that he did not expect Beijing to “retaliate too much”.