Police detained dozens of people at an anti-Kremlin protest on Thursday, including 82-year-old Lyudmila Alexeyeva, one of Russia's most respected rights activists.
Alexeyeva was among those seen being pushed into five buses as police broke up the protest on a central Moscow square.
Her detention drew criticism from rights groups and the head of the presidential human rights council, Ella Pamfilova, who said on Ekho Moskvy radio that she was working to get all the protesters released.
Reached late in the evening by cell phone, Alexeyeva said she was in the office of the Moscow police chief, who had promised to release all of the protesters. She was free but said she would not leave until the others were released.
She had arrived at the New Year's Eve protest dressed as the Snow Maiden, the companion of Grandfather Frost. Police had forbidden the protest on the grounds that it would interfere with New Year's festivities.
Small groups of protesters Thursday shouted "Freedom" or "End Putin's Reign" before being detained or shoved away from the square.
Since coming to power 10 years ago, Vladimir Putin has rolled back many of the democratic achievements of the 1990s.
The protest was a repeat of actions held on the 31st of July, August and October. The timing is a nod to the 31st Article of the Russian constitution, which guarantees the right of assembly.
City authorities banned all the protests and sent police to break them up. But this is the first time that police have detained Alexeyeva, a leading Soviet dissident who has continued to lead the fight for democracy and human rights in Russia. She was among this year's recipients of the European Union's top human rights award.
Opposition leader Eduard Limonov was detained as he approached the square, as he has been ahead of previous protests, according to activists. He spent 10 days in jail in November on charges of organizing the Oct. 31 protest and resisting arrest.
Thursday's protest ended an hour after it started when 40 helmeted riot police joined the hundreds of city police in clearing the square.
"They're breaking the law by doing this," said Viktor Shenderovich, a well-known political satirist and opposition activist. "They are violating our constitutional right to assembly.
Police spokesman Arkady Bashirov said more than 50 protesters had been detained, but because they were taken to several different stations an exact number was not available. At least 100 people were seen being taken away in police buses.