Russian authorities say police have detained more than 60 people demonstrating at a freedom of assembly rally in Moscow.
Dozens of police officers heavily cordoned off the central square where the rally was held Tuesday and hauled away the protesters in buses.
The demonstrators chanted "Russia without Putin!" as the police led them away.
Among those detained were several prominent activists, including opposition politician and former Deputy Prime Minister Boris Nemtsov.
Opposition groups have been calling for protests on the 31st day of each month to honor the 31st article of the Russian Constitution, which guarantees the right of assembly. Most of the rallies have been banned or dispersed by police.
Russian authorities also detained some 60 protesters Tuesday in St. Petersburg, where hundreds gathered for a similar rally.
In an interview published Monday, Russian Prime Minister Vladimir Putin said police would continue to break up the opposition protests unless the protesters obtained official permission to rally.
Some information for this report was provided by AP, AFP and Reuters.