Svetlana Gannushkina, chairwoman of Russia's Civic Assistance committee for refugees, told RFE/RL's Uzbek Service in Moscow that the refugees are being held at a detention facility in the Ivanovo region.
"After a lengthy judicial process it was decided on Friday, March 2, that they should be released from detention, but this decision still has not been carried out," Gannushkina said. "At first their excuse was that it was a weekend, but now it is already Monday afternoon [and they are still being detained]."
The activists say the refugees, who have been held for around 20 months, face extradition to their home country.
Uzbek authorities have been asking for their extradition, accusing them of involvement in a protest in the eastern Uzbek city of Andijon in May 2005.
The 12 Uzbeks, who have refugee status from the UN High Commissioner for Refugees, deny the accusations.