Memorial spokeswoman Yulia Klimova said tax police seized more documents on March 26 in addition to those taken during searches at Memorial’s other two Moscow offices during inspections in the past week.
Klimova said police were interested in documents about registration and finances.
Prosecutors in St. Petersburg are also conducting an audit of Memorial’s antidiscrimination center in that city.
Dozens of nongovernmental organizations in 16 Russian regions are being checked to determine whether they are in compliance with laws passed last year concerning foreign financing.
Amnesty International’s Moscow office was among the NGOs searched on March 25.
The head of Amnesty’s Moscow office, Sergei Nikitin, said police told him he would be called to the prosecutor’s office for questioning.