Mexican president Enrique Pena Nieto has compared US presidential candidate Donald Trump to the notorious dictators Adolf Hitler and Benito Mussolini.

The Mexican leader’s comments, published on Tuesday morning (AEDT) in the Excelsior newspaper, were the most inflammatory denunciation of Trump from any world leader.

President Nieto criticised Mr Trump’s “populism”, warning that similarly “strident rhetoric” had resulted in “global conflagration”, a reference to World War II.

• ‘We want to find MH370 more than anything’
• Possible North Korea crisis predicted next year
• Margie Abbott ‘sidelined by Peta Credlin’

“There have been episodes in human history, unfortunately, where these expressions of this strident rhetoric have only led to very ominous situations in the history of humanity,” he told Excelsior.

“That’s how Mussolini got in, that’s how Hitler got in, they took advantage of a situation, a problem perhaps, which humanity was going through at the time, after an economic crisis.

Trump recently asked his followers to raise their right hands to pledge to vote for him. Photo: Jenna Johnson / Twitter

“And I think what [they] put forward ended up at what we know today from history, in global conflagration. We don’t want that happening anywhere in the world.”

Donald Trump is currently the front-runner for the Republican party nomination. Throughout his campaign, the New York businessman and reality TV star has made increasingly outrageous and arguably racist comments, which only seem to boost his poll numbers.

A step too far, even for Trump

Mr Trump’s most controversial comment to date was a recent promise to torture terrorists and kill their families, both of which would violate international law.

This position was criticised by US military officials. Former CIA director General Michael Hayden said the armed forces would refuse to follow such an illegal order.

“If he were to order that once in government, the American armed forces would refuse to act,” General Hayden told HBO.

After the backlash, Mr Trump backtracked, saying he would not in fact break the law if he became US president.

“I feel very, very strongly about the need to attack and kill those terrorists who attack and kill our people … I do, however, understand that the United States is bound by laws and treaties and I will not order our military or other officials to violate those laws and will seek their advice on such matters,” he said in a statement.

Mexico refuses to pay for Trump’s wall

Donald Trump thrives on controversy. Photo: Getty

To win the Republican nomination outright, Mr Trump needs at least 1237 delegates. He currently has 374 to Ted Cruz’s 300, while Senator Marco Rubio trails with approximately 146.

In the Excelsior interview, the Mexican president made it clear that his government would never acquiesce to Trump’s demand that it pay for a wall along the US border — one of the billionaire’s key election promises.

“There is no scenario,” he said. “I have to say that I regret [the plan], and of course, I can’t agree with this American politician’s position.”

Mr Trump has outraged Mexicans by describing those who enter the US illegally as criminals, rapists and drug dealers.

It is because of remarks like these that moderate Republicans are desperate to thwart the rise of Trump. Last week, former nominee Mitt Romney, who has become an elder statesman of sorts, made the extraordinary decision to lambast Trump as a “phoney” and a “fraud” in a widely publicised press conference.

Mr Romney’s comments were interpreted by some analysts as a signal of disunity and in-fighting among Republicans.

The more you denounce, the more he grows

An expert on US politics, who spoke to The New Daily before President Nieto’s comments, said the unfortunate side effect of denunciations of Trump were that “it makes people who like unreasonable things think that they’re on the right side”.

President Nieto rules out helping Trump meet his election promise. Photo: Getty

“It’s very, very hard to knock him back,” Flinders University head of American studies Professor Don DeBats said.

“I think the only real way to do that is to go after his actual track record, not what he says, but what he’s done.”

Despite his Hitler comparison, President Nieto told Excelsior his administration would try to maintain a respectful relationship with whoever becomes the next US president.

If Trump does win the Republican nomination, he is likely to face former Secretary of State Hillary Clinton as the Democrat nominee.

Prof DeBats said the Democrats would be worried about such a matchup.

“The Democrats know that Trump will get Democratic votes too,” he said.

“The angry cohort is not just Republicans. It’s the same bunch of people who have been knocked down by the change in the US economy and US culture. They’re as Democrats as much as they are Republicans.”