UPDATE 1-Russian forces kill 7 suspected militants in Caucasus-report

(Updates with more suspected militants killed)

MOSCOW, March 12 (Reuters) - Russian security forces killed seven suspected Islamist militants in the restive North Caucasus province of Kabardino-Balkaria on Tuesday, the Interfax news agency reported.

Three suspected militants were killed when security forces fired on two cars whose drivers did not respond to demands to show identification documents, Interfax cited unidentified law enforcement officials as saying.

Separately, the agency also quoted Russia's federal anti-terrorist committee as saying four more alleged militants, suspected of illegal arms sales, were killed in the same province on Tuesday and another eight people were arrested.

The reports made no mention of any casualties among security forces. Police could not immediately be reached for comment and the Interfax account of the violence could not be independently confirmed.

Deadly exchanges of gunfire between police and suspected militants are common at road checkpoints and elsewhere in Russia's North Caucasus, a string of provinces hit by an Islamist insurgency rooted in two separatist wars in Chechnya.

Kabardino-Balkaria, west of Chechnya, is mostly Muslim but has a sizable Christian minority.

President Vladimir Putin's 13 years in power have been marred by violence in the North Caucasus, and attacks by the insurgents elsewhere, and he has called repeatedly for ethnic and religious peace during a new term that started last May.

The region is in the spotlight before the 2014 Winter Olympics Russia will host in the Black Sea resort of Sochi at the western end of the Caucasus mountain range.

Russia is trying to ensure security at the games, which Putin hopes will help improve Russia's image abroad, but which have also become a declared target of the Islamist umbrella group Caucasus Emirate, which has in the past claimed responsibility for bloody attacks in the country. (Writing by Steve Gutterman and Gabriela Baczynska; Editing by Lisa Shumaker and Alistair Lyon)