More than 600 people have been detained over an unauthorized protest in Moscow, amid reports of police violence.
Protesters had gathered in the Russian capital after authorities disqualified a number of opposition candidates from standing in local elections.
Leading activist Lyubov Sobol was arrested before she could reach the rally, attended by 1,500 people.
Video from the rally shows officers using their batons against demonstrators while making arrests.
Russian officials initially said there had been just 30 arrests and 350 attendees.
Monitoring group OVD-Info, which runs a hotline for reporting detentions, had been keeping a running toll, which rapidly jumped from a few dozen arrests to several hundred.
Officers in riot gear had earlier moved into the capital and warned people not to protest. Russian news agency TASS reported that one police officer had been injured while making an arrest.
But protesters also reported mistreatment at the hands of police.
Footage broadcast on Russian television and shared on social media showed police pin people to the ground, kicking or using batons on them. One man told Dozhd TV channel that one such person had been removed from the police van for a beating after asking officers to identify themselves.
Banned from rallying, the organizers designated this a Saturday “stroll” with multiple gathering points along Moscow’s boulevard ring.
So it wasn’t always obvious who was protesting. The old ladies on the benches? The man walking his dog? The food delivery man, right in the middle of it?
To the riot police, out in huge numbers in helmets and body armour, it didn’t seem to matter much. They erected metal barriers and blocked off roads.
Then a woman’s voice came over a loudspeaker, to declare that the security forces included conscripts. “Your sons are among them!”, she said. Then those conscripts – and the professionals – swooped and grabbed people. I saw one man being carried off upside down still strapped to his bicycle.