Abubakar Shekau, the leader of the Nigerian Boko Haram militants is replaced by Mahamat Daoud who has not been heard of before, Chad's President Idriss Deby says without mentioning the reason.
Speculation arose that Shekau has been killed since he had not featured in the group's recent videos. He was last heard from in March, when he released an audio message pledging allegiance to ISIS.
Daoud was open to dialogue, said Deby, whose troops have been involved in battling Boko Haram.
The Chadian leader was said to be holding peace talks with Boko Haram last year, according to the BBC's Nigeria correspondent Will Ross.
Nigeria alongside military coalition partners of Niger, Chad and Cameroon has claimed successes in fighting Boko Haram since February, forcing the group’s fighters out of the territory it used to control.
Chad announced two weeks ago that its forces killed 117 Boko Haram militants in a two-week military campaign to clear up the islands on Lake Chad, which militants use as hiding-places and bases to launch attacks.
In Boko Haram attacks, more than 600 people have been killed in Nigeria alone since President Muhammadu Buhari, who based his presidential campaign on defeating Boko Haram, took office at the end of May.
Nigeria’s new President Muhammadu Buhari vowed to eliminate Boko Haram after he was sworn in at the end of May.
He flew to the United States to meet with President Barack Obama to ask for increased US military assistance in fighting the militant group.
Boko Haram has been fighting a six-year insurgency being responsible for the deaths of over 30,000 civilians and security personnel, and causing about 1.5 million people to flee their homes, in a bid to establish a state of its own in northern Nigeria.