Russian investigators say a man accused of plotting unrest with other opponents of President Vladimir Putin has turned himself in and confessed.
Leonid Razvozzhayev is said to have made admissions in a high profile case.
However, his supporters dispute the account, saying he was detained by force in the Ukrainian capital Kiev.
In a video posted online, the activist claims he has been tortured.
“On 21 October, he turned to the main investigation directorate of the Investigative Committee of Russia, with a written surrender statement in which he informed, in detail, that he along with Sergey Udaltsov, Konstantin Lebedev and other people, had been preparing mass unrest in the Russian Federation,” said Vladimir Markin, a spokesman for the Russian Investigative Committee.