"Three leaders and four active members of a secret cell, who held gatherings of the organisation's members, during which they spread the ideology of Tablighi Jamaat, which undermines the foundations of Islam, and involves new supporters in destructive activities, were detained", the FSB said in a statement.
The service seized extremist literature and various attributes belonging to the organisation. The police opened a criminal case against the cell. The organisation included natives of Central Asia.
Tablighi Jamaat is a global missionary movement urging Muslims to practice the form of Islam that was practised during the times of the prophet Muhammad. It is estimated to have between 12 million and 150 million adherents. It has been classified as an extremist group by Russia since 2009.