Alexandra Krylenkova of Memorial says six uniformed men wielding clubs forced the staff out of the office Thursday and confiscated computer hard drives.

A prosecutor says the search was based on suspicion the group had financed an opposition newspaper that authorities closed last year for allegedly inciting racial hatred.

Krylenkova says that was "just a pretext" to harass a group, which often criticizes authorities.

City prosecutor's office spokesman Sergei Kapitonov says the search followed an investigation into the closed daily. Kremlin critics have come under increasing pressure from Russian authorities in recent years.