Russian opposition activist Sergei Udaltsov has been briefly detained by Moscow police while protesting in front of the State Duma, Russia's lower chamber of parliament.
Udaltsov's wife, Anastasia Udaltsova, wrote on Twitter that police took her husband to the Tver district police department.
He was released by the police on September 13 about 90 minutes later.
Udalstov wrote on Twitter that he and activist Aleksei Vorontsov were released after what he described as "a preventive talk" with police.
Udaltsov and Vorontsov were staging single-man protests next to the State Duma building to demand amnesty for inmates across Russia in connection with the 100th anniversary of the October Revolution that brought Bolsheviks to power in 1917.
Udaltsov was released from prison on August 8 after serving a 4 1/2-year prison sentence over his role in organizing a May 2012 protest against President Vladimir Putin and his government on Moscow's Bolotnaya Square.
In July 2014, Udaltsov was convicted of organizing "mass disorder" in connection with the protest, which erupted into violence that demonstrators and police blame on each other.