At least 10 people have been injured in an explosion at a supermarket in the Russian city of St Petersburg.

One person was said to be in serious condition after the detonation of an improvised explosive device (IED).

President Vladimir Putin described the blast, at the Perekrestok supermarket chain late on Wednesday, as a terrorist act.

No group has said it carried out the attack, which officials say produced a blast equivalent to 200g (7oz) of TNT.

Russia's investigative committee said the device contained "striking" elements.

The blast took place in an area of the shop that housed lockers for storing bags.

The property was quickly evacuated and there were no reports of a fire, but images circulating on social media in Russia showed extensive damage in an area of the store close to the tills.

Mr Putin commented on the blast at a military awards ceremony on Thursday. Officials had earlier suggested the attack was being treated as attempted murder.

Earlier this month, the Russian president and his US counterpart Donald Trump spoke by phone after information provided by the CIA helped Russian security services foil an attack on St Petersburg's Kazan cathedral.

At the time, Russia's Interfax news agency reported that a group had been planning attacks at a number of sites. Several people were reportedly detained.

Source: BBC