Russian authorities have opened a terrorism investigation following an explosion in the southwestern city of Stavropol that has killed at least seven people and wounded some 40 others, many in critical condition.
The bomb blast occurred near a cultural center on May 26, shortly before the start of a scheduled show by a Chechen dance company.
Authorities say the explosive device carried the force of 200-250 grams of TNT, and contained metal shards.
Stavropol's governor, Valery Gayevsky, described the bombing as an "unprecedented, brutal provocation."
Chechnya's President Ramzan Kadyrov blamed "Russia's enemies" for the blast.
There has been no reported claim of responsibility for the attack.
Stavropol Krai, which borders the violence-hit republics of the Russian North Caucasus, has previously seen attacks by militants, but not in recent years.
compiled from agency reports