Bakhrom Khamroyev has continued to highlight the Uzbek authorities use of Russian intelligence services to detain opposition figures living in exile in Russia.
Last month, Khamroyev gave a well-publicized Moscow press conference condemning Uzbek President Islam Karimov's rule and documented human rights abuses.
US-based rights watchdog Memorial said it suspects Khamroyev has been detained by the same Russian secret service agents against whom he had levelled serious allegations.
"These facts suggest that Khamroyev's arrest was political in nature," Memorial said in a statement, calling on Russian prosecutors to investigate his arrest.
11 year exile
Khamroyev was forced to flee Uzbekistan in December 1992 in a government crackdown on his opposition group Birlik.
Later he published the prominent opposition newspaper Kharakat, which was distributed in the United States in both Uzbek and Russian.
The newspaper attempted to throw light on the oppressive practices of Karimov, including allegations of the torture and "disappearances" of opposition figures.
Khamroyev had also sent some issues of his newspaper to his native country, a source of irritation for the Uzbek authorities, according to Memorial.
Last November, the British ambassador to Uzbekistan, Craig Murray, criticised Tashkent for not registering a single opposition organisation and the imprisonment of between 7,000 to 8,000 innocent citizens on the pretext of fighting terrorism.
Karimov has become an important US ally in its military campaign in Afghanistan, although his regime comes under frequent criticism from human rights groups.