The Moscow-based Memorial human rights center says Mirsobir Khamidkoriev disappeared on June 9 as he was waiting in his car while his wife, Eleonora Isaeva, was in a pharmacy buying medicine for their son.
A witness said two men forced their way into Khamidkoriev's car and that they all drove away.
Khamidkoriev, who is seeking political asylum in Russia, was arrested by Russian authorities last year on Tashkent's request.
He was released in August 2013 after a prosecutor found the charges leveled by Tashkent to be inconsistent.
Memorial says Khamidkoriev had escaped previous abduction attempts in the past.
Khamidkoriev's lawyer, Illarion Vasilyev, said he has informed Russian authorities about his client's possible "illegal" extradition to Uzbekistan.