Six people have been detained in St Petersburg suspected of recruiting for so-called Islamic State (IS) and aiding terrorist activity, investigators say, BBC said.
The suspects are from Central Asian countries and have been active since November, Russian officials add.
There is no evidence they are connected with Akbarzhon Jalilov, a Kyrgyzstan-born man suspected of bombing St Petersburg’s metro.
Monday’s attack killed 14 people and injured almost 50.
Those detained had been recruiting other Central Asian immigrants in St Petersburg “to carry out terrorist crimes” and to join “illegal armed groups”, including IS, Russia’s state investigative committee said in a statement, BBC concluded.