Russian investigators detain six on terror suspicion, no links found to St Petersburg's bomb attack

Six people have been detained in St Petersburg on suspicion of recruiting for Islamic State and aiding terrorist activity, Russian investigators said on Wednesday.

There is no evidence the detainees, who are citizens of Central Asian states, are in any way linked to Monday's bomb attack in a St Petersburg metro train, Russia's state investigative committee said in a statement.

The detainees are suspected of being active since November 2015 in recruiting other Central Asian immigrants for "terrorist activity" and for Islamic State as well as another banned Islamist movement Nusra Front.

Extremist Islamist literature has been found during a search of the detainees' living quarters, the statement added.