Russian protest leader Sergei Udaltsov arrived Friday for questioning and was expected to be charged in a probe into televised allegations that he was plotting riots against President Vladimir Putin. Udaltsov obeyed a summons to the Investigative Committee, which has said that it plans to charge him Friday with a plot to hold mass riots with international funding. 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. He walked into the Investigative Committee's office ahead of his questioning scheduled for 0600 GMT without commenting to journalists, only holding up his hands in a gesture acknowledging his supporters. "This will be a trial of the Putin regime. Come to the Investigative Committee to support me and other political prisoners," Udaltsov wrote minutes later on Twitter. There had been speculation that Udaltsov, who is currently under travel restrictions, might try to flee after the chief investigative body said officially that it planned to charge him Friday. 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. Udaltsov, who has had his apartment searched in the probe, has rejected the allegations as the "delirium of a lunatic." His aide Konstantin Lebedev has already been detained and charged. An assistant to a parliamentary lawmaker, Leonid Razvozzhayev, has also been charged and detained. He has told rights activists that he was kidnapped by masked men in Ukraine who held him prisoner until he signed a confession. Lawyer Mark Feigin on Thursday said that Razvozzhayev had drawn up a statement to investigators withdrawing his written and videotaped confession, saying that it was made under pressure.