In a long-awaited report, the UN accuses China of "serious human rights violations" against Uyghur Muslims in Xinjiang province, China denies allegations.
The report was released on Michelle Bachelet's final day as UN High Commissioner for Human Rights after four years in office.
The report accuses China of using vague national security laws to restrict the rights of minorities and establishing "systems of arbitrary detention."
It claim prisoners had been subjected to "patterns of ill-treatment" including "incidents of sexual and gender-based violence."
Others said they faced forced medical treatment and "discriminatory enforcement of family planning and birth control policies."
Beijing denies the claims of abuse and insists it is a victim of a Western-led slander campaign. They argue that the camps are a tool to fight terrorism.
China claim that Uyghur militants plot bombings, sabotage and civic unrest as part of a violent campaign for an independent state.
It says Xinjiang has now become socially stable and economically developed, referring to it as "the greatest human rights achievement."
"This so-called 'assessment' is a politicised document that ignores the facts, and fully exposes the intention of the US, Western countries and anti-China forces to use human rights as a political tool."
- China's Delegation to the UN Human Rights Council
The Xinjiang region in north-western China, have about 12 million Uyghurs citizens, majority of whom are Muslims.
An estimate of over a million people have been detained at camps, according to human rights organizations.
