Opposition leader Alexei Navalny, who was detained yesterday in Moscow, announced himself last night that the police had let him out of the police station, reported Btv.
Yesterday morning the Moscow police detained him "for repeated appeals for participation in an unauthorized public event".
He was arrested before going to Nizhny Novgorod for unauthorized action. The police have compiled an administrative protocol.
The Simonean court in Moscow will consider the administrative case against him on 2 October.
This is the third detention for Navalni for the past six months, the previous two before his rallies in Moscow on 26 March and 12 June this year.
The 41-year-old opposition eader is considered to be Vladimir Putin's main rival in the presidential election next year if they allow him to run, added Btv.