Police have detained several participants in an unauthorized rally in central Moscow's Triumfalnaya Square.
The young activists displayed an antigovernment banner outside the square's Tchaikovsky Concert Hall and lit a smoke bomb on October 31.
The protest was part of an opposition campaign known as Strategy 31 that holds regular protests on the last day of 31-day months to draw attention to Article 31 of the Russian constitution, which guarantees the right to demonstrate.
Three activists of the Strategy 31 campaign were arrested in Nizhny Novgorod on October 31.
Also on October 31, Eduard Limonov, a leader of the unregistered opposition Other Russia party, was detained in Moscow while on his way to the Triumfalnaya Square with a group of party members.
It was not immediately clear why Limonov was detained.
Based on reporting by Interfax and RIA-Novosti