Moscow: Eight members of extremist cells have been arrested in connection with last week's deadly bombing on the subway in St Petersburg, Russia's intelligence chief said yesterday.

Akbardzhon Dzhalilov, a 22-year old Kyrgyz-born Russian national, has been identified as the bomber. Russian authorities have not reported his possible links to extremist groups, but an unidentified law enforcement official said investigators were checking information that Dzhalilov may have trained with the Islamic State group in Syria. He reportedly flew to Turkey in November 2015 and spent a long time abroad.