Federal prosecutors charged left-wing opposition leader Sergei Udaltsov and Leonid Razvozzhayev with organizing so-called riots two months after President Vladimir Putin won his third election.
The two activists could face ten years in prison for staging an opposition "riot" on Bolotnaya Ploshchad in Moscow last May, a charge they contest.
In a statement the Russian Investigative Committee said Wednesday that both men, part of Russia's Left Front Socialist movement, had pleaded not guilty and refused to testify.
“Both Razvozzhayev and Udaltsov were questioned, both did not admit their guilt and refused to give testimony. The investigation of this criminal case continues,” the statement said.
There are 12 protesters facing trials for their parts in alleged violent acts during anti-Putin protests in May 2012.
Razvozzhayev has been in detention since October. Udaltsov is under house arrest, which he says is related to his intent to run in Moscow's mayoral election this September. If convicted, Udaltsov will not be able to run for or hold office.
“The authorities saw a danger in me because they understood I can mobilize people,” Udaltsov said. “The aim of my arrests has been to isolate me as a political figure, especially during the election period.”