A United Nations committee has called on the US to "unequivocally and unconditionally" reject and condemn racist hate speech and crimes.
The UN Committee on the Elimination of Racial Discrimination (CERD) was responding following events in Charlottesville, after white supremacists and anti-fascists clashed.
One woman was killed in the violence. Heather Heyer (32) died when a car was driven into a crowd at the protest.
The CERD says high-level politicians and public officials also need to reject and condemn racist events throughout the country.
This could be seen as a reference to US President Donald Trump, who was initially criticised for not condemning the far right groups.
In a decision issued under its early warning and urgent action procedure, the committee said: "There should be no place in the world for racist white supremacist ideas or any similar ideologies that reject the core human rights principles of human dignity and equality."
Irish woman Anastasia Crickley, CERD chairperson, said: "We are alarmed by the racist demonstrations, with overtly racist slogans, chants and salutes by white nationalists, neo-Nazis, and the Ku Klux Klan, promoting white supremacy and inciting racial discrimination and hatred".
Anastasia Crickley | Image: European Union Agency for Fundamental Rights
In addition to the criminal investigation of the individual who ploughed his car into the crowd, UN experts have asked US authorities to undertake "concrete measures to address the root causes of the proliferation of such racist manifestations."
"We call on the US government to investigate thoroughly the phenomenon of racial discrimination targeting, in particular, people of African descent, ethnic or ethno-religious minorities, and migrants", Ms Crickley added.
It has called on the US to ensure that the rights to freedom of expression, association and peaceful assembly are not exercised "with the aim of destroying or denying the rights and freedoms of others."
It has also asked the US to provide "the necessary guarantees" so that such rights are not misused to promote racist hate speech and racist crimes.
