Russian President Vladimir Putin says a blast that ripped through a supermarket in the country’s second-largest city was a terrorist attack.

At least 13 people were injured on Wednesday evening after an improvised explosive device went off at a storage area for customers’ bags at the supermarket in St Petersburg.

Investigators said the device contained 200 grams of explosives and was rigged with shrapnel to cause more damage.

No-one has claimed responsibility for the explosion, which occurred at a branch of the Perekrestok supermarket chain in the city’s north-west Kalininsky district.

Mr Putin made his comment on Thursday at an awards ceremony at the Kremlin for troops who took part in Russia’s Syria campaign, but did not offer any details. He also said another terrorist attack had been thwarted in St Petersburg but did not elaborate.

The Russian President has previously spoken about Russia’s operation in Syria as a pre-emptive strike against terrorism at home.

He said the threat of attacks at home would have been much worse if Russia had not intervened in Syria.

“What would have happened if those thousands [of terrorists] that I have just spoken about, hundreds of them had come back to us, trained and armed,” he said in comments to Russian news agencies.

Putin thanked Trump for CIA tip

Earlier this month, Mr Putin telephoned US President Donald Trump to thank him for a CIA tip that helped thwart a series of bombings in St Petersburg — Mr Putin’s home town.

The Federal Security Service said seven suspects linked to the Islamic State group were arrested in connection to the alleged plot.

The Kremlin said the arrested suspects had planned to bomb the city’s Kazan Cathedral and other crowded sites.

In April, a suicide bombing in the St Petersburg subway left 16 people dead and wounded more than 50.

Russian authorities identified the bomber as Akbardzhon Dzhalilov, a 22-year-old Kyrgyz-born Russian national.

-ABC/AAP