A still image of suspect Akbarzhon Jalilov walking at St Petersburg's metro station is shown in this police handout photo obtained by 5th Channel Russia April 4, 2017. [Photo/Agencies]

The blast took place in a train carriage in the tunnel between two metro stations in St. Petersburg, Russia's second largest city, killing at least 14 people and wounding dozens.

"The conclusions of the genetic examination and the recording of the CCTV cameras give the investigators reasons to believe that it was Dzhalilov who committed the terrorist act in the train," said the RIC in a statement.

The statement did not disclose whether Dzhalilov had accomplices or connections to the Islamic State or other terrorist groups.

According to the statement, Dzhalilov left an additional explosive device at a third metro station, which has been defused by investigators.

Dzhalilov himself died in the blast, Interfax news agency quoted RIC spokeswoman Svetlana Petrenko as saying.

RIA Novosti news agency and some Kyrgyz media outlets reported that Dzhalilov was born in Kyrgyzstan and attained Russian citizenship.

Born in 1995, Dzhalilov left Kyrgyzstan for Russia with his parents in 2011. Later, his parents returned to Kyrgyzstan, while Dzhalilov himself remained in Russia to earn money, Kyrgyz news agency 24.kg quoted their close relatives as saying.