Russian security officers armed with automatic rifles searched on Wednesday the Moscow offices of a rights group that represents the interests of Russian nationals in the European Court of Human Rights, the group said.

Members of the Federal Security Service (FSB) searched an office used by Justice Initiative and its partner organisation Astreya and confiscated the telephones of employees and photographed their passports, the group’s spokeswoman said.

The FSB sought access to an office used by the group’s director, but was not allowed in, Ksenia Babich said, adding that the security officers did not give an explanation for the search.

She said it began after officers searched a neighboring office in the same building used by an unrelated auditing company.

Justice Initiative has offices in the North Caucasus in southern Russia and has helped hundreds of Russian citizens file cases over rights violations at the European Court of Human Rights.

President Vladimir Putin has tightened controls on non-governmental organizations, requiring those with foreign funding to register as “foreign agents”, and introducing legislation outlawing groups seen as “undesirable.”

The FSB did not immediately respond to a request for comment.