Members of the Uighur Muslim ethnic group are calling on China to post videos of their relatives who have disappeared into a vast system of internment camps.

The social media campaign follows the release of a state media video showing famed Uighur musician Abdurehim Heyit, who many believed had died in custody.

China has come under increasing scrutiny for the camps holding an estimated 1 million minority Muslims in its far west Xinjiang region.

Beijing says these facilities are vocational training centers where Uighurs, Kazakhs and others receive free skills education.

In a rare show of public criticism from a majority Muslim nation, Turkey on Saturday called China's treatment of Uighurs "a great cause of shame for humanity." Its foreign ministry condemned the camps, citing Heyit's reported death.