US President Donald Trump has threatened to exclude Canada from a new NAFTA agreement after negotiations to rewrite the pact ended without an agreement on Friday.

“There is no political necessity to keep Canada in the new NAFTA deal. If we don’t make a fair deal for the US after decades of abuse, Canada will be out,” he tweeted.

“Congress should not interfere with these negotiations or I will simply terminate NAFTA entirely & we will be far better off.”

Mr Trump earlier confirmed “insulting” comments that he’d first made off the record regarding his unwillingness to work with Canada on the North American Free Trade Agreement.

During an interview with Bloomberg News on Thursday, Mr Trump said he was not willing to compromise with Canada on revising NAFTA.

“Here’s the problem. If I say no ― the answer’s no,” Mr Trump said about a possible compromise. “If I say no, then you’re going to put that, and it’s going to be so insulting they’re not going to be able to make a deal. ... I can’t kill these people.”

“Off the record, Canada’s working their ass off,” Mr Trump said. “And every time we have a problem with a point, I just put up a picture of a Chevrolet Impala.”

The Impala is produced in Oshawa, Ontario.

The Toronto Star reported those off the record comments. Journalist Daniel Dale tweeted out this morning to confirm that no one at Bloomberg leaked him the Trump comments.

NAFTA negotiations with Canada will resume next week, the White House said on Friday.

Mexico and the US reached a preliminary agreement on Monday.