Four alleged members of Islamic State who were preparing attacks in Moscow have been arrested, Russian security agents said.
The Federal Security Service, or FSB, the main KGB successor agency, said the suspects arrested in Moscow on Thursday were preparing to strike at the capital's transport network.
The agency said the four were working under directions from IS in Syria to prepare attacks using self-made explosive devices.
The FSB said the suspects were planning to join IS in Syria after the attack.
It did not give their names, saying only the group included citizens of Russia and ex-Soviet Central Asian nations.
The arrests follow last month's suicide bombing in St Petersburg's subway which left 16 dead and wounded more than 50.