Members of the Turkic Uyghur Muslim ethnic group are calling on China to post videos of their relatives who they say have disappeared into a vast system of internment camps.
A social-media campaign was launched on February 12 under the hashtag #MeTooUyghur following the release of a video by China's state media showing Uyghur musician Abdurehim Heyit, who was said to have died in custody.
The authenticity of the clip could not be verified, and it was not clear where and by whom it had been filmed.
"My husband #MuhtarRozi must be free immediately! #MyParents must be released right now I am very anxious about them. Where are they now? Are they all safe or not?" an Istanbul-based woman with the Twitter handle maryamhanim tweeted.
"Show me the Video of them as you show AbdurehimHeyit's video," she also wrote.
Beijing faces growing international pressure over its policies toward Uyghurs and members of other Turkic-speaking mostly Muslim indigenous communities in the northwestern region of Xinjiang.
A report by a UN panel of experts last year said that an estimated 1 million of them were being held in "counterextremism centers."
They said millions more had been forced into reeducation camps.
China says that the facilities are "vocational education centers" aimed at helping people steer clear of terrorism and allow them to be reintegrated into society.