Algerian Djamel Okacha has replaced Abdelhamid Abou Zeid as leader of al Qaeda-linked group AQIM in the Sahara region, Algerian Ennahar TV said on Sunday.
Abou Zeid was killed by Chadian soldiers in northern Mali a few weeks ago.
Okacha, also known as Yahia Abu El Hamam, joined AQIM northern Mali in 2004, a security source with knowledge of AQIM told Reuters.
"He was present at the attack against a military barracks in Mauritania in 2005, and he was also present in the killing of an American in 2009," the source said, referring to aid worker Christopher Leggett.
Okacha, 34, is close to AQIM's leader Abdelmalek Droukdel as they belong to the Group of Algiers, a reference to militants born in the capital region.
"Okacha is Droukdel's right hand. They have spent 12 years together in the north, before Okacha joined the south," the security source told Reuters.
Okacha's priority is to reorganize AQIM after it registered the losses of two heavyweight leaders, Abu Zeid and Mokhtar Belmokhtar, the source said.
France launched a joint military campaign with some African armies in Mali in January to break Islamist rebels' hold on the region, saying the militants posed a risk to the security of West Africa and Europe.