Russian security services said on Wednesday that the leader of the self-proclaimed Caucasus Emirate was killed in a special operation involving air strikes in Russia's Dagestan region on August 11.
Magomed Suleimanov was among four fighters killed by security forces in the district of Untsukul, according to Russia's National Antiterrorist Committee.
Suleimanov, also known as Abu Usman Gimrinsky, was formally announced as the leader of the "Caucasus Emirate" in July, after previous leader Aliaskhab Kebekov was also killed by Russian forces in April.
The group's founding leader Doku Umarov died in March 2014 during a raid carried out by Russian special forces.
The pro-militant website Kavkaz Center confirmed the death of Suleimanov, 39, saying he "became a martyr" in the August 11 operation near the mountain village of Gimry, his home village.
Recently some members of the group had pledged allegiance to ISIS, but Magomed Suleimanov lashed out at commanders and fighters who joined an "un-Islamic group that kills Muslims."
The Caucasus Emirate, active from 2007, operates mainly in the North Caucasus with the aim of expelling Russian forces from the area and creating an independent "Islamic State."