About forty protesters, including several opposition leaders, were detained at a demonstration dubbed the "March of Freedom" in Moscow on Saturday.
Hundreds of protesters braved subzero temperatures and the prospect of detention — the march was not authorized by City Hall — to register their opposition to President Vladimir Putin's regime.
The event, which was timed to mark the first anniversary of the protest movement, failed to eclipse earlier demonstrations in size or fervor, a result that seemed likely to spark a new round of soul searching and finger-pointing within the opposition about leadership and tactics.
Opposition leaders Alexei Navalny and Sergei Udaltsov were quickly detained by police officers at the protest that had a start time of 3 p.m., as were Ksenia Sobchak, Ilya Yashin and other prominent figures.
The detentions of Navalny and Udaltsov come after a week that saw both men come under increasing pressure from authorities. On Friday a criminal case was opened against Navalny and his brother, Oleg, on charges of large-scale fraud and money laundering, and earlier this week investigators accused Udaltsov of taking marching orders from a Georgian politician.
Police estimated the number of protesters at 500, while Udaltsov said 5,000 had gathered at Lubyanskaya Ploshchad, across the street from the former KGB headquarters.