Talking to RFE/RL's Uzbek Service, Yelena Ryabinina of the Moscow-based group Civic Assistance said a uniformed policeman and a plainclothes security officer came to the NGO's office earlier today and took Rustam Muminov away.
Ryabinina, who runs the group's program for political immigrants from Central Asia, said the police said they were him "to the nearest police station." Subsequent inquiries indicated that he is not there.
Muminov was arrested in Russia's Lipetsk Oblast in February based on an Uzbek arrest warrant.
Authorities in Tashkent want him in connection with the popular uprising last year in the eastern Uzbek city of Andijon.
After a Lipetsk court last month cleared him of all charges and ordered his release, Muminov moved to Moscow.