According to the UN, there may be as many as a million Chinese Uyghyrs and other ethnic minorities who have been forced into re-education camps over the past two years.
The UN is calling for their immediate release as well as a thorough investigation.
In China’s far western province of Xinjiang, about a thousand camps have been built – according to the Chinese government – to stop terrorism.
Some former detainees have managed to leave China and have reached neighbouring Kazakhstan.