Two men in Russia's St. Petersburg have been held for allegedly robbing beer from a shop by threatening the shop assistant with a hand grenade.

"After they got two beer bottles, the men put the grenade on the counter and ran off," a police spokesman said Monday.

The two were detained soon afterwards.

This was the second time a grenade was used in the city in recent days. Last week, a man set off a hand grenade in a conflict, leaving one man injured.