Former president of Mexico Vicente Fox took aim at U.S. President Donald Trump on Wednesday, calling him a "wild animal" whose ideas about Mexico reveal "economic ignorance."

In an interview with CBC News Network, Fox said Canada and Mexico must band together in the face of Trump's assertion that the North American Free Trade Agreement should be scrapped, as well as his plan to build a wall between the U.S. and Mexico.

Former Mexican President Vicente Fox calls Trump 'wild animal' 1:31

"That's the right, the prerogative of the United States to decide if they want to build a wall within their territory," said Fox, who was president of Mexico from 2000 to 2006.

"What we will never, ever, ever accept is to pay for that wall in Mexico. That's a crazy idea; it's out of any consideration."

Fox noted that Mexico's current president, Enrique Pena Nieto, has told Trump that Mexico will not pick up the tab for a wall dividing their two nations.

​"Congress in Mexico has already stated legally that that cannot happen," said Fox.

If Trump attempts to fund the construction of a wall by taxing remittances on migrant workers, he said, Mexico will respond in turn. "Nobody will win with these crazy wars," said Fox. "Everybody will lose."

"But when you have a crazy horse and wild animal in front of you that doesn't understand reason, then you have to act in a different manner, eye-for-eye, teeth-for-teeth."

Canada and Mexico must 'join together,' says Former Mexican President Vicente Fox 1:39

Fox has become a vocal opponent of Trump, frequently tweeting his discontent with Trump policies in English.

.<a href="https://twitter.com/realDonaldTrump">@realDonaldTrump</a> represents the old-world. The world has moved on his ideas and it's making it clear in the streets <a href="https://twitter.com/hashtag/StandUpToTrump?src=hash">#StandUpToTrump</a>. —@VicenteFoxQue

Addressing criticism in recent days that Canada is betraying Mexico by considering a new trade agreement with the U.S. to the exclusion of Mexico, Fox said it's important for Canada and Mexico to remain united.

"The best thing we can do is go hand-by-hand together, Canada and Mexico, and confront this crazy situation, this false prophet and this economic ignorance."

Fox added that both his country and Canada "have a lot to lose" in revenue and jobs if trade with the U.S. is restricted.

"I invite Canada to join together with Mexico and defend our mutual interests."

Watch the whole interview with CBC News Network below.