"I think there is ample evidence that both police and other security forces have been and are continuing to systematically practice torture, in particular against dissidents or people who are opponents of the regime," Nowak told RFE/RL on April 10.
Nowak also questioned how former Uzbek Interior Minister Zakir Almatov was able to obtain medical treatment in Germany last year and return to Uzbekistan.
Almatov served as interior minister during the crackdown in Andijon in May 2005. The UN has said it suspects him of using torture during his term.
Nowak said that, as a signatory to the UN Convention on Torture, Germany should have detained Almatov.