Alexander Tarasenkov AP / PA Images Alexander Tarasenkov AP / PA Images / PA Images

Updated 10.05am

THE DEATH TOLL from yesterday’s terror attack on the metro in St Petersburg, Russia has risen to 14 people.

An explosion, believed to have been set off by a male suicide attacker after boarding a train, rocked through a metro station leaving dozens more injured.

Authorities said that they had also defused a bomb at a second metro station.

Russia’s investigate committee had said it was probing an “act of terror”, but said it was looking into all possible causes of the blast.

Later, the Interfax news agency later cited unspecified sources as saying police suspected the blast was caused by a suicide bomber linked to radical Islamists.

The agency said authorities believe the suspect, a 23-year old who came from ex-Soviet Central Asia and was linked to radical Islamist groups, carried the explosive device onto the train in a rucksack.

The security services in the central Asian country of Kyrgyzstan have said that the attacker was from the country.

“The suicide bomber in the Saint Petersburg metro was a Kyrgyz national Akbarjon Djalilov… born in 1995,” a spokesman for the country’s security services told AFP.

Asked about the report, Putin spokesman Dmitry Peskov wouldn’t comment, saying it’s up to law enforcement agencies to comment on details of the probe.

Amateur video broadcast by Russian TV showed people lying on the platform of the Technological Institute station, and others bleeding and weeping just after the damaged train pulled in.

Blast victims lie near a subway train hit by a explosion at the Tekhnologichesky Institut subway station in St.Petersburg, Russia. AP / PA Images AP / PA Images / PA Images

“Everything was covered in smoke. There were a lot of firefighters,” Maria Smirnova, a student on a train behind the one affected by the blast, told independent TV station Dozhd.

The entire St Petersburg metro system was shut down and evacuated, but partial service resumed after about six hours.

Some residents of St Petersburg, a city of five million people, responded with both dismay and determination.

“They won’t succeed in breaking up our country. We are all citizens of one country despite various political views and religious beliefs,” said 24-year-old Alexander Malikov, who brought flowers and candles to an improvised memorial outside one of the stations.

Vladimir Putin laying flowers down near the metro station Dmitri Lovetsky / AP/Press Association Images Dmitri Lovetsky / AP/Press Association Images / AP/Press Association Images

Three days of mourning have been announced for the city.

With reporting from the Associated Press and AFP

Read: Terror investigation launched after 10 die in blast in St Petersburg underground system