Belmokhtar, an Algerian citizen, was regarded as a key member of Al-Qaida in the Islamic Maghreb (Aqim) until he reportedly fell out with leader Abou Zeid and formed the Khaled Abu al-Abbas Brigade, also known as Masked Brigade or the Signatories in Blood.
In January 2013 he organised the attack on Algeria's In Amenas gas plant, which ended with the deaths of 38 hostages.
He also worked with the Islamist group, Mujao, to drive the Tuareg separatist group, MNLA, out of the Malian city Gao.
In March the government of Chad, which joined France in putting down the rebellion in north Mali, claimed that its troops had killed both Belmokhtar and Abou Zeid, although the US is still offering five millions dollars (3.6 million euros) for information leading to his detention.
Now several security sources have told journalists that Belmokhtar has left Mali, where French troops and US drones were searching for him, has taken refuge with other armed Islamists in Libya.
He is planning more attacks on Westerners and their interests, they say.