US President Donald Trump has said all trade talks with Canada have been terminated following what he called a fraudulent advertisement in which former president Ronald Reagan spoke negatively about tariffs.

"Based on their egregious behavior, ALL TRADE NEGOTIATIONS WITH CANADA ARE HEREBY TERMINATED," Trump wrote on Truth Social on Thursday.

Ontario premier Doug Ford said this week that the ad with anti-tariff messaging had caught Trump's attention. The ad showed Reagan, a Republican, criticising tariffs on foreign goods while saying they caused job losses and trade wars.

"I heard that the president heard our ad. I'm sure he wasn’t too happy," Ford said on Tuesday.

Trump has used tariffs as leverage on many countries around the world.

His trade war has increased US tariffs to their highest levels since the 1930s and he has regularly threatened more duties, sparking concerns among businesses and economists.

Canadian Prime Minister Mark Carney said on Thursday that Canada will not allow unfair US access to its markets if talks on various trade deals with Washington fail.

Trump imposed tariffs on Canadian steel, aluminum and autos this year, prompting Ottawa to respond in kind. The two sides have been in talks for weeks on a potential deal for the steel and aluminium sectors.

Next year, the United States, Canada and Mexico are due to review their 2020 continental free-trade agreement. (Reuters)