Police detained about 20 people on Tuesday during the weekly opposition rally in downtown Moscow.
“About 20 people have been detained and sent to the police station,” a police spokesperson said.
Tuesday's rally, "Elections Without Opposition Is a Crime," was held on Triumfalnaya Square, a frequent site for opposition gatherings.
A total of 50 people, primarily journalists, gathered at the Square, shouting opposition slogans and distributing leaflets.
Last week's rally grabbed headlines when police detained a six-year-old boy, the son of opposition activist Sergei Aksyonov.