A police officer was killed in an attack by unknown assailants in Russia's North Caucasus republic of Dagestan, a local police spokesman said on Monday.

"Unknown assailants opened fire on the head of criminal investigation department Maj. Alishab Magomedov while he was on his dacha in the town of Kaspiisk," the spokesman said.

He added that investigators are working at the scene of the crime.

Russia's mainly Muslim North Caucasus republics, especially Chechnya, Dagestan and Ingushetia, have seen an upsurge of militant violence lately, with frequent attacks on police and officials.

The Kremlin has pledged to wage "a ruthless fight" against militant groups but also acknowledged a need to tackle unemployment, organized crime, clan rivalry and corruption as causes of the ongoing violence.

MAKHACHKALA, July 26 (RIA Novosti)