MOSCOW, April 4. /TASS/. Russian investigators may seek the assistance of their foreign counterparts in cracking the St. Petersburg subway blast case, Kremlin spokesman Dmitry Peskov said on Tuesday.

"It is our investigators who will be making the decision," the presidential spokesman said.

"No doubt, it cannot be ruled out that the Russian side may resort to such [foreign] assistance, if needed," the Kremlin spokesman stated.

Responding to a question about whether investigators were considering the version of a suicide bomber as the prime cause of the blast, the Kremlin spokesman said this was one of the versions under investigation.

An unspecified explosive device went off at about 2:40 Moscow time (11:40 GMT) on a subway train travelling between the Tekhnologichesky Institute and Sennaya Ploshchad subway stations in St. Petersburg on Monday.

Russia’s Investigative Committee are treating the blast as a terror attack but is also checking other possible versions.

According to the Russian Health Ministry’s latest data, 14 people were killed and 49 were hospitalized with injuries in the subway bombing.