A woman participates in a rally against racism and fascism in Athens, Greece, on March 17, 2018. (Photo: Xinhua/Marios Lolos)

UN Secretary-General Antonio Guterres on Tuesday called for tolerance on the occasion of the International Day for the Elimination of Racial Discrimination.

"We cannot allow extremist ideologies to become normalized and legitimized in our societies. The answer is to preach and practice tolerance, inclusion and respect for diversity," Guterres told a commemorative meeting of the UN General Assembly.

The International Day for the Elimination of Racial Discrimination, which falls on March 21, commemorates the Sharpeville massacre in 1960, where police opened fire and killed 69 people peacefully demonstrating against apartheid in South Africa.

The memory of Sharpeville lives on in this annual UN observance. Sadly, racism, xenophobia and intolerance persist in countries and among communities around the world, said Guterres.

Despite considerable progress in the 70 years since the adoption of The Universal Declaration of Human Rights, which recognizes the inherent dignity and equal and inalienable rights of all members of the human race, people all over the world still endure constraints on -- or even total denial -- of their human rights, said the UN chief.

"Gender inequality remains a pressing issue, with untold women and girls facing daily insecurity, violence and violation of their rights. We are also seeing an alarming rise in xenophobia, racism and intolerance, including anti-Semitism and anti-Muslim hatred. Far-right political parties and neo-Nazi viewpoints are seeing a resurgence. Refugees and migrants are systematically denied their rights and unjustly and falsely vilified as threats to the societies they seek to join, despite the proven benefits they bring."

The world has a long way to go before the discriminatory attitudes, actions and practices are brought to an end, he said.

"So, on this international day, let us all consider how we can better promote tolerance, inclusion and respect for diversity in all nations and among all communities. Let us work to eliminate messages of hatred -- the concept of 'us' and 'them,' the false attitude that we can accept some and reject and exclude others simply for how they look, where they worship or who they love."

He warned of the grave consequences of racist thinking -- discrimination, slavery and genocide.

He also called on people to stand up to leaders "who spread their toxic vision of racial superiority, especially when they couch it in sanitized language to denigrate migrants and foreigners."

Guterres encouraged greater debate and openness, and the exchange of different views, experiences and perspectives. He particularly called for leadership -- leadership that is courageous enough and principled enough to counter intolerance, racism and discrimination in all its forms.