United Nations: The UN rights chief took a swipe at US Republican presidential frontrunner Donald Trump Friday, accusing him of exploiting fear and resorting to bigotry in campaigning that he warned was a ‘road to violence.’

Zeid Ra’ad Al-Hussein delivered the blunt criticism in a speech at a university in Cleveland, Ohio, where Republicans will gather in July to choose their White House nominee.

Over the past months, Trump has promised to build a wall on the US-Mexico border to keep out migrants and to ban Muslims from entering the United States.

‘Bigotry is not proof of strong leadership,’ said Zeid, the UN High Commissioner for Human Rights.

‘Hate speech, incitement and marginalisation of the ‘other’ are not a tittering form of entertainment, or a respectable vehicle for political profit,’ he said.

‘To casually toss this gasoline on the smouldering embers of fear is to risk great harm to a great nation. Discrimination is a powerful and profoundly destructive force.’

Zeid did not refer to Trump by name but he deplored the ‘frontrunning candidate for president’ who declared his support for torture, and took aim at the ‘multiple candidates’ who advocate surveillance and other invasive measures targeting Muslims.

‘We have heard these calls to hatred — calls stigmatizing and demonising minorities, beginning the validation of violence,’ he said.

In December, the rights chief charged that Trump was being ‘grossly irresponsible’ when he proposed a ban on Muslims entering the United States.

Zeid, a Jordanian diplomat who has been UN rights chief since 2014, said the election campaign had given way to a ‘full-frontal attack’ on America’s ‘hard-won tenets of decency and social cohesion.’

‘This is also the road to violence, not perhaps visible — not yet.’

He warned of ‘heavy costs’ paid by ‘many innocent people, sometime in the future, who will fall victim to violent acts’ because they have been painted as the enemy.

Turning to the Republican convention in July, Zeid said ‘the world’s eyes will turn to Cleveland, and it is my deepest hope that the people of this country will demonstrate their profound understanding of human dignity and human rights.’