The head of the World Trade Organization said on Wednesday he would not get involved in a slanging match with Donald Trump after the US presidential candidate suggested withdrawing from the WTO.

Trump, having earlier threatened to renegotiate or rip up the North American Free Trade Agreement, told NBC on Sunday that if he takes the White House he might "renegotiate or pull out" of trade deals if the WTO challenges his policies.

Republican Trump added that "These trade deals are a disaster ... (the) World Trade Organization is a disaster," insisting he would not let the WTO override his plans to impose punitive taxes on firms which shift production offshore.

But the WTO's director general Roberto Azevedo said he would not rise to the bait.

"I do not intend to open a discussion on this subject -- as I am not a (presidential) candidate," Azevedo told a news conference in Geneva.

"Everybody knows what I think of the WTO and its importance for international trade and job creation," the Brazilian added, saying he would put himself forward for a second term at the head of the body after his first ends in September next year.

In May, Trump raised eyebrows when he slammed China on trade, blaming the Asian behemoth for weakening the US economy and taking American jobs.

"We can't continue to allow China to rape our country, and that's what we're doing, Trump told a campaign rally, insisting that the United States had "a lot of power with China."

Source: AFP