Russian law enforcement agencies have detained 140 people in Moscow on suspicion of involvement in Islamic extremist groups, the FSB security service said on Friday.
"As the result of investigative activities at the house No 8 at the Danilovskaya embankment, employees of law enforcement bodies detained 140 people of whom more than 30 are foreign nationals," the Moscow branch of the FSB state security agency said in a statement carried by the Interfax news agency.
The statement said the detained were taken to a police station.
The FSB was not available for comment.
The raid comes after Russian President Vladimir Putin and his US counterpart Barack Obama vowed to step up cooperation between their special services in the wake of the Boston bombings allegedly carried out by two brothers of Chechen origin.