Russian President Vladimir Putin has said a blast that ripped through a St Petersburg supermarket yesterday injuring shoppers was the result of an act of terrorism.

Officials said yesterday the blast was caused by a "homemade explosive device with the power equivalent to 200 grammes of TNT filled with lethal fragments".

Ten people were injured in the attack.

Mr Putin was speaking at an awards ceremony in the Kremlin for Russian military servicemen and women who served in Syria.

"You know that yesterday in St Petersburg a terrorist act was carried out," Mr Putin told the audience.

"And that recently the Federal Security Service prevented another attempted terrorist act."

Mr Putin said the security situation in Russia would be much worse, however, if thousands of Russian citizens who had fought with the so-called Islamic State militant group in Syria had been allowed to return home.