Abubakar Shekau, the leader of Nigeria's Boko Haram militant group, denied the claims that he had been killed or ousted as chief of the militant group in an audio recording released on Sunday.
Shekau denied the claims of the Chadian president Idriss Deby that he had been replaced calling him a hypocrite" and a "tyrant" in the eight-minute long recording.
"It is indeed all over the global media of infidels that I am dead or that I am sick and incapacitated and have lost influence in the affairs of religion," Shekau said.
"It should be understood that this is false. This is indeed a lie. If it were true, my voice wouldn't have been heard, now that I am speaking,” he added.
The audio recording was shared through social media.
Idriss Deby had declared on August 12 that efforts to fight neighbouring Nigeria's Boko Haram militant group had been successful in weakening the group and would be up "by the end of the year".
The SITE Intelligence Group verified the authenticity of the message, and an AFP correspondent with extensive experience of reporting Boko Haram said it exactly resembled Shekau's voice in previous recordings.
The video message was verified by the SITE Intelligence Group and an AFP correspondent which said Shekau's voice in the recent audio recording exactly matched the previous recordings.
Before the recent audio recording, speculation arose that Shekau had been killed, since he had not featured in the group's recent videos and was last heard from in March, when he released an audio message pledging allegiance to ISIS.
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.