Russia on Wednesday detained anti-Putin protest leader Sergei Udaltsov for questioning as he faces criminal charges over allegations that he plotted mass riots. Udaltsov has been detained for 48 hours for questioning by the Investigative Committee, Udaltsov’s wife Anastasiya told the popular Moscow Echo radio station. ‘Sergei Udaltsov has been arrested for 48 hours,’ the official Twitter account of his Left Front opposition movement wrote, adding that his two assistants were detained for the same period. Udaltsov’s lawyer Violetta Volkova wrote on Twitter that Udaltsov had not yet been formally detained, however, ‘but they will soon finalise it, I think.’ Udaltsov, the shaven-headed leader of the radical Left Front movement, has become one of the most prominent organisers and speakers at mass rallies in Moscow opposing President Vladimir Putin.