MAKHACHKALA: At least 13 people have been killed and scores more injured in two powerful explosions in Russia's restive North Caucasus.

Emergency ministry chief physician in Dagestan, Kazanfar Kurbanov, said on Friday that more than 120 people were injured and 15 of them are in critical condition. Authorities are treating the blasts on Thursday night as an attack by insurgents.

Dagestan is plagued by frequent attacks on police and civilians by Islamist insurgence.

The insurgency spread to the region from neighboring Chechnya where Russian federal forces have fought two wars with separatists since 1994.