Eight suspects including a woman were arrested on Thursday in connection with the terrorist bombing on St Petersburg's metro, Russian officials have announced.
Earlier in the day police held three suspected accomplices to the attacker, who was named as Kyrgyzstan-born Akbarzhon Dzhalilov, 22. They also deactivated an explosive device in the apartment where they suspects lived.
The latest arrests come after six people were held on suspicion of recruiting the so-called Islamic State and the Al-Nusra Front following Monday's bombing, which killed 14 people.
There has been no claim of responsibility for the attack.
The seven people were from Central Asian countries and investigators say they were recruiting for IS.
The bombing of a subway train in Russia has drawn condemnation from world leaders.
A blast has ripped through an underground train in Russia's second-largest city on Monday.