Russia's counter-terrorism agency says it has raided the hideout of armed militants in the North Caucasus and killed 11 of them.

The National Anti-Terrorist Committee said the militants were part of a group whose members had pledged allegiance to the Islamic State group.

An Islamic insurgency has long simmered in the predominantly Muslim North Caucasus republics of southern Russia. The region, which includes Chechnya and Dagestan, has recently become a fertile ground for IS propaganda and recruitment.

Russia has intensified its airstrikes against IS in Syria in retaliation to the bombing of its passenger plane in Egypt.

The Russian agency said the raid was conducted Sunday morning near Nalchik, the capital of the Kabardino-Balkaria republic, and the militants were killed after opening fire on law enforcement officers.