OVD-Info, a group which monitors police action against opposition figures, said Andrei Pivovarov was arrested at Pulkovo airport and was being transferred to the Investigative Committee.
Open Russia said on Thursday it had decided to end its operations in Russia to protect its members from the risk of being jailed.
Russia declared the London-based group "undesirable" in 2017, effectively banning its activities. Its allies in Russia continued their activism under the same name, but as a separate legal entity to try to protect themselves from prosecution.
(Reporting by Vladimir Soldatkin; Editing by Peter Graff)
Source: Reuters