US President Donald Trump on Tuesday said that he would double incoming steel and aluminium tariffs on Canadian imports from 25 percent to 50 percent, adding that these would take effect "tomorrow morning".

Trump – in the statement which comes after the Canadian province of Ontario imposed an electricity surcharge on three US states – also threatened to "substantially increase" tariffs on cars coming into the United States on April 2.

He said the further tariffs would "permanently shut down the automobile manufacturing business in Canada".

He also revived threats that the country would become "our cherished Fifty First State". (Agencies)