One serviceman was also killed, NAK's website said.

　　The anti-terror operation started at 05:00 Moscow time (0100 GMT) in the village of Dolakovo. After the militants were blocked in a private household and refused to surrender, the fighting has started which lasted for three hours.

　　Four militants were killed, two of them have been identified as Ozdoyev brothers. According to NAK, they masterminded a suicide bombing on the administrative border's check-point last October which killed two policemen.

　　No civilians were hurt during the operation, NAK said.

　　Violence is common in the Russia's North Caucaus where the militants have been active since mid-1990s.