The family of prominent Tatar activist Rafis Kashapov says he has been detained by security officials who also raided his home in the city Russian city of Chally.
Kashapov, the leader of the NGO Tatar Public Center (TIU) in Chally, was arrested in the morning on December 28 upon his return from Turkey, where he had undergone medical treatment, the family said.
They say authorities have confiscated Kashapov's laptop and mobile phone. He was taken for questioning to Tatarstan's capital, Kazan, where he is still being held without charges.
According to posts on Kashapov's Facebook account, he held meetings with Turkish activists during his visit to Turkey.
The TIU campaigns to preserve Tatar national identity, language and culture.
The group once was accused of "igniting interethnic hatred" after it held a public rally in support of the use of the Tatar language in secondary schools in Tatarstan, a region in central Russia in which traditionally Muslim ethnic Tatars make up a small majority of the population.