GENEVA (AFP) -- The UN's rights chief warned Wednesday that Donald Trump's statements pointed to a "dangerous" figure emerging on the world stage if he won the US presidency.

At a press conference in Geneva, UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein said he was "not keen or intent on interfering in any political campaign."

But, he said, in light of the "unsettling" and "disturbing" comments from the US presidential candidate it was only right to sound the alarm.

"If Donald Trump is elected, on the basis of what he has said already, and unless that changes, I think that it is without any doubt that he would be dangerous from an international point of view," Zeid said.

He referred to Trump's call to bring back interrogation techniques that legal experts say amount to torture.

And, he said, Trump's attacks on "vulnerable communities" such as Muslims, immigrants and minorities "suggest that they may well be deprived of their human rights."

Last month, Zeid launched a scathing attack on populists such as Trump and Dutch far-right leader Geert Wilders, calling for action to halt "demagogues and political fantasists."

He had also compared Trump to Hungary's Prime Minister Viktor Orban, France's leader of the National Front Marine Le Pen, and leading Brexit campaigner Nigel Farage.

Those comments sparked a harsh reaction from Russia's ambassador to the UN in New York Vitaly Churkin earlier this week.

Churkin complained the rights chief had overstepped his authority and had no business criticising foreign heads of state and government.

Churkin denied that he had taken issue with the remarks directed at Trump, but his remarks fuelled renewed speculation that the Kremlin is working to help the Republican candidate's campaign. 

Zeid dug in Wednesday.

"We are not a political office, so we are not going to get into ... politics, but where it affects the rights of people and especially vulnerable groups, we will speak," he said, insisting: "I see no reason to curb what it is that we are saying."

Zeid insisted that his office wholeheartedly "supports the freedom of expression."

"We believe it to be not just a right, but the greatest check against tyranny" he said.

"However, when you fan resentment and seek as a political leader to pin blame on a specific community for deeper problems, real problems, this is highly regrettable," he said.

Zeid pointed out that "populists often try to (say) that if you criticise a populist leader, you are criticising those who support him or her. And this is false."

"There are very real fears that are being stoked and exploited," he warned, stressing that "it is within the mandate of the office to speak out where we feel that vulnerable groups are being targeted for reasons that are misplaced."