A Muslim cleric has been shot dead in the Russian republic of Dagestan, amid what experts say are rising tensions between moderate Muslims and radical Islamists in the volatile region.

Russian police say two unidentified gunmen opened fire on Kalimulla Ibragimov early Tuesday morning in the city of Derbent as he was on his way to morning prayers. His father and brother were also killed in the attack.

Ibragimov was said to preach Salafism, a radical movement that promotes an ultraconservative brand of Islam.

His murder is the latest in a series of attacks on clerics in Russia's restive North Caucasus. At least three others have been killed in attacks so far this year.

Moscow has struggled to contain an Islamic insurgency in the largely Muslim region, nearly a decade after fighting two wars against separatists in Chechnya. Russia claims the region is largely under control, but sporadic bombings, assassinations and attacks on government facilities and troops are continually carried out by Muslim insurgents fighting to set up an Islamic state there.