Russia on Friday charged protest leader Sergei Udaltsov with plotting mass riots in a controversial probe that has also seen the detention of an activist who claims he was tortured into making a confession. Udaltsov was charged after being summoned by the Investigative Committee for questioning over an alleged plot to hold mass riots with international funding to topple President Vladimir Putin. Two men have already been charged in the probe, including Leonid Razvozzhayev, an aide to an opposition parliamentary lawmaker, who has retracted a confession that he said he made under pressure after being kidnapped apparently by Russian security agents in Ukraine. Udaltsov, 35, the shaven-headed leader of the radical Left Front movement, has been one of the most prominent organisers and speakers of mass protests against Putin and has been detained numerous times for public order offences. \"I did not plan, prepare or organise mass riots,\" he told journalists after leaving the Investigative Committee. \"I support peaceful mass protests but not violent ones.\" Udaltsov has been charged with plotting mass riots but not carrying them out for reasons beyond his control. \"Udaltsov did not admit his guilt,\" the Investigative Committee said in a statement. He was not arrested as had been widely expected but remains under travel restrictions that prevent him from leaving Moscow. Russia launched a criminal probe after pro-Kremlin national channel NTV this month showed a documentary with hidden camera footage that alleged that Udaltsov and others were planning an uprising funded by a Georgian lawmaker. His aide Konstantin Lebedev has been detained and handed the same charge, which could lead to a jail term of up to 10 years. The other detainee, Razvozzhayev, is also a member of Udaltsov\'s Left Front movement. \"I consider this case fabricated. The charges are absurd,\" Udaltsov said. \"I think the fact that two of my comrades today are behind bars is absolutely unjust.\" Razvozzhayev told rights activists who visited him in prison that he was kidnapped by masked men in Ukraine who held him prisoner, denying him food and drink for several days, until he signed a confession. He has drawn up a statement to investigators withdrawing his written and videotaped confessions, saying they were made under pressure, his lawyer Mark Feigin said Thursday. Moscow city court will hear his complaint against his arrest on November 7, another of his lawyers, Anna Stavitskaya, told the RAPSI legal news agency. The Investigative Committee\'s spokesman insisted Friday that Razvozzhayev\'s retraction of his testimony would not affect the case. \"If Mr Razvozzhayev and his associates think that their testimony or denial of their testimony are a key factor in the case, I can disappoint them,\" spokesman Vladimir Markin said in televised remarks. \"The investigation has enough other clues and proof, received and checked through investigation and operations.\" Ukraine\'s security service said Friday it was conducting a formal check into Razvozzhayev\'s \"urgent departure for Russia\" after the United Nations\' refugee agency said he disappeared while seeking asylum in Kiev. Experts see the charges as part of a crackdown by Putin on the protest movement that has involved harsher punishments for public order offences and a criminal probe into charismatic protest leader Alexei Navalny. \"The authorities are very concerned at the wave of protests and are prepared to take the most serious measures,\" Sergei Kovalyov, chairman of Memorial rights group, told AFP. \"Both the laws and the courts are ready for this. And it is happening already: they are reviving political repressions.\"