Gunmen have killed a leading Muslim professor and his nephew in the restive southern Russian republic of Dagestan.

Police say Maksud Sadikov and his nephew Zalimkhan Musayev were mowed down in a hail of bullets Tuesday night outside Sadikov's home in Makhachkala, Dagestan's capital. The attackers wounded another man before fleeing the scene.

Regional investigators said they believe Sadikov's murder was linked to his professional activity. He was the head of the Institute of Theology and International Relations in Makhachkala and an outspoken critic of radical Islam.

Dagestan's President Magomedsalam Magomedov called the murder an attack on Dagestani society that must not go unpunished.

The Council of Muftis, a major Muslim organization in Russia, also condemned the murder, saying it challenges efforts to promote peace in the Caucasus.

Russia's North Caucasus region is beset by persistent violence linked to an Islamist insurgent movement. Chechen separatists fought two wars against Russia in the 1990s. Although major fighting has ended in the North Caucasus, attacks on police and government targets in the region continue, particularly in Dagestan.