Seven militants were killed recently in Russia's North Caucasus republic of Dagestan, the country's National Anti-Terror Committee (NAC) said Monday.

"A police operation against militants started in a forest in the Kizlyar district on May 10," the NAC was quoted as saying by the Interfax news agency.

Among the seven killed, one was a police-officer-turned militant who assisted his fellows traveling freely in the region, and another one bombed the railroad track in the Tarumovsky district of Dagestan last year.

The militants murdered several local figures in recent years who openly criticized illegal armed groups in the region, according to the NAC.

Machine guns, submachine guns and pistols were seized during the operation, the NAC said, adding that search for other militants continues.

Violence is common in Russia's North Caucasus, especially in the republics of Chechnya, Dagestan and Ingushetia, with militants frequently mounting attacks against police officers and authorities.