Officials from Russia's Federal Penitentiary Service (FSIN) say they have found no evidence to support claims by a political activist that he was abused and tortured while in prison.
FSIN officials on November 28 said they had investigated the claims of prisoner Ildar Dadin at the request of Russian human rights ombudswoman Tatyana Moskalkova.
Dadin, 34, who is serving a 2 1/2-year prison sentence after being convicted of participating in more than one unsanctioned demonstration, made the abuse claims in an open letter earlier this month.
Russian opposition activists regard him as a political prisoner.
"The investigation did not confirm the use of forbidden methods of influence on Dadin or the illegal use of physical force against the convict," FSIN Deputy Director Valery Maksimenko told journalists in Moscow.
He called Dadin "a very talented faker with great artistry and great imagination."
Dadin's supporters have called for an independent investigation into his assertions of abuse against himself and other prisoners.