Russian security forces have killed 12 people including leading Islamist fighters in the North Caucasus republics of Kabardino-Balkaria and Chechnya, officials and local media said.

Two law-enforcement officials were also killed in the fighting, they said on Thursday.

Russia is fighting an Islamist insurgency in the North Caucasus where fighters carry out almost daily attacks more than a decade after federal forces ousted a separatist government in Chechnya.

Fighters in the North Caucasus say they are fighting for an Islamic state in the strip of provinces along Russia's southern

border. Rights activists say the insurgency is driven by poverty and anger at the tactics of the security forces.

Police and security officers surrounded a home in the Kabardino-Balkaria's regional capital, Nalchik, and stormed it after the suspected fighters inside refused to surrender and opened fire, the National Anti-Terrorist Committee said.

The government forces killed all eight occupants of the home, including four senior leaders of the fighters and two women who were the wives of fighters and took part in the gun battle, it said in a statement.

Violence is more frequent in Chechnya, Ingushetia and Dagestan further southeast from Kabardino-Balkaria, though Moscow fears it may spill over to other regions.

Russia's Interfax news agency quoted Chechnya's Kremlin-backed regional leader, Ramzan Kadyrov, as saying on Thursday that four fighters and two security forces members were killed in fighting in Chechnya.

He said the fighters had been planning to commit "serious crimes" but did not elaborate.