In Moscow, activist Ildar Dadin was detained near the FSB building, Sergei Ozhich told OVD-Info.
According to him, Dadin held a one-man picket demanding the release of the organizer of the Russian Marches, Yury Gorsky, who was taken away for interrogation by the FSB on July 5 as a suspect in the case of public calls for extremist activities (part 1 of article 280 of the Criminal Code).
UPD: Dadin was taken to the Meshchansky police station. They take explanations from him.