WASHINGTON - US President Donald Trump said on Thursday that all trade negotiations with Canada were terminated because a "FAKE" Canadian advertisement was designed to influence the US Supreme Court's decision.

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

The Ronald Reagan Presidential Foundation accused the advertisement made by the government of Ontario of "using selective audio and video" from former US president Ronald Reagan's national radio address on trade in 1987, according to the foundation's statement.

The foundation said Ontario does not have the permission "to use and edit the remarks" and warned it was reviewing its legal options.

Trump said the advertisement was made with the intention to "interfere with the decision of the US Supreme Court, and other courts".

The Supreme Court will begin hearing arguments about the legality of Trump's global tariffs early next month and will rule on it.

Canadian Prime Minister Mark Carney said earlier on Thursday that his country will not allow unfair US access to Canadian markets if their trade talks fail.