Russian police have detained about two dozen opponents of President Vladimir Putin who tried to protest in Moscow and St. Petersburg against restrictions on freedom of assembly.
Opposition figure Eduard Limonov and at least 14 activists from his Other Russia group were detained when they tried to stage a protest on Moscow's central Triumph Square without permission from authorities.
At least seven protesters reportedly were detained in St. Peterburg.
Since 2009, activists have tried to hold protests on the last day of every month that has 31 days in order to draw attention to what they say is government suppression of the right to free assembly.
The right to assemble is enshrined in Article 31 of the Russian Constitution but frequently is denied as officials refuse to issue permits.
With reporting by Reuters and Interfax