Russian officials say security forces have surrounded an apartment building in the southern city of Nalchik, where suspected Islamic militants are believed hiding.

Earlier, in a separate operation, police detained three suspected militants in the city, the capital of Russia's Kabardino-Balkaria Republic. Officials say they seized grenades and at least one handgun, as well as Islamic extremist literature.

Russia has intensified its campaign against militant groups since more than 330 people, half of them children, were killed in a school hostage-taking in the southern city of Beslan last September. Wanted Chechen separatist leader Shamil Basayev has taken responsibility for the attack.

Russia has been battling separatists in Chechnya for most of the past decade.

Some information for this report provided by AP and Reuters.