The death toll from the St Petersburg metro bombing has risen to 14, according to Russian health minister Veronika Skvortsova.
Russian agency Ria Novosti quoted Ms Skvortsova as saying on Tuesday the total had risen from 11.
Earlier on Tuesday, Kyrgyzstan's State Committee for National Security said in a statement it believed one suspect behind the bombing was a Kyrgyz-born Russian citizen it identified as Akbarzhon Dzhalilov.
The Kyrgyz intelligence agency said Russian authorities informed them about the man, aged between 21 and 22, but they were not aware of his specific role in the bombing. The intelligence agency said it is cooperating with Russian authorities to help the investigation.
Interfax news agency said authorities believed the 23-year-old suspect was linked to radical Islamist groups.
Russia's state investigative committee said the bomb may have been detonated by a man whose body parts were found in one of the train carriages. It declined to give the man's name, in contrast with its Kyrgyz counterpart.
"It has been ascertained that an explosive device could have been detonated by a man, fragments of whose body were found in the third carriage of the train," the committee, which has sweeping powers, said in a statement.
"The man has been identified but his identity will not be disclosed for now in the interests of the investigation," the statement added.
An unidentified explosive device went off at 2.20pm on Monday, on a train leaving the Technology Institute station and heading to the Sennaya Ploshchad station, Russia's National Anti-Terrorist Committee said.
The blast came as Russian President Vladimir Putin was visiting the city, his hometown. He said investigators are looking into whether the explosion was a terror attack.
Interfax cited a source saying the blast was caused by a bomb filled with shrapnel.
A second bomb was found and defused by police.
Kyrgyzstan is a former Soviet republic which gained independence in 1991.
Additional reporting by agencies
