A website associated with the Al-Qaeda-linked Islamic Movement of Uzbekistan (IMU) announced on August 4 that its leader Osman Adil was killed in a drone attack in Pakistan.
According to the site, Adil's deputy, Osman Ghazi, had succeeded him as the new leader of the group.
It is not clear when and in what circumstances Adil was killed.
The IMU is a militant Islamist group formed in 1991.
Its objective was to overthrow President Islam Karimov of Uzbekistan, and to create an Islamic state under Shari'a.
Operating out of bases in Tajikistan and Taliban-controlled areas of northern Afghanistan, the IMU launched a series of raids into southern Kyrgyzstan in 1999 and 2000.
Its training camps are currently operating in Pakistan's region of Waziristan.