MOSCOW (AP) — Security officers in Moscow raided the offices of Alexei Navalny, the most prominent foe of President Vladimir Putin and the governing United Russia party.

Navalny has been jailed repeatedly in recent years for organizing or participating in unsanctioned protests. His Foundation for Fighting Corruption organization has produced reports alleging corruption by top figures including Prime Minister Dmitry Medvedev.

Navalny was taken from the office by officers of the federal court bailiffs’ service that forced their way into the officie. But the service later said he hadn’f been detained.

Lyubov Sobol, an attorney with Navalny’s foundation, said the officers claimed to be searching for evidence connected to a case against the foundation’s director, Ivan Zhdanov.

A criminal case was opened against Zhdanov in August for failing to follow an order to remove a video version of a report claiming corruption by Medvedev.