Russian police and security agents have detained 140 people at a mosque in Moscow on suspicion of involvement with Islamic extremism.
A statement from the Federal Security Agency reported by Russian news agencies said among those detained in the Friday action were 30 citizens of unspecified foreign countries.
The detentions come a week after the two suspects in the fatal Boston Marathon bombing were identified as originating from the Russian region of Chechnya and sympathizing with Islamic extremists.
There were no immediate reports of charges being filed. The security agency referred The Associated Press to a district office, where the telephone was not answered.
The reports cited the agency as saying the mosque previously has been visited by people who had been involved in preparing or carrying out terrorist attacks.