This screen grab image taken on February 18, 2015 from a video made available by Islamist group Boko Haram shows Boko Haram leader Abubakar Shekau making a statement at an undisclosed location
Lagos (AFP) - Claims that Nigeria's Boko Haram has been "decapitated" have been spectacularly rebuffed by the jihadists' leader, yet his first broadcast in months may not see off an impending mutiny, say analysts.
Abubakar Shekau released an eight-minute audio recording on Sunday -- his first since March -- denying claims by Chadian leader Idriss Deby that he had been replaced, and dismissing the president as a "hypocrite" and a "tyrant".
The tirade was a reaction to Deby telling reporters in N'Djamena last week that Boko Haram was no longer led by the fearsome Shekau and that his successor, whom he named as "Mahamat Daoud", was open to talks with the government.
Security analysts accept the Shekau recording as genuine and many experienced observers are taking Deby's claims with scepticism, pointing out that similar reports have proven untrue in the past.
But Ryan Cummings, chief security analyst at South African consultancy Red 24 and an expert on the Nigerian insurgency, described the Chadian head-of-state's claims as "not without merit".
Cummings believes Boko Haram may be an umbrella movement comprising many disparate factions rather than a monolithic organisation and says internal rivalries "would be no means be a new development for the sect".
He points to the formation of Ansaru, a splinter group formed in 2012 on the back of ideological differences and a leadership struggle between Shekau and a high-ranking Boko Haram commander known as Khalid al-Barnawi.
"So this does highlight that a precedent for leadership squabbles and factionalism does exist within the Boko Haram entity," Cummings told AFP.
- 'Top dog' -
Boko Haram has been waging a six-year uprising against the Nigerian state, claiming more than 15,000 lives, but the jihadists' recent extension of their northeastern insurgency across borders has brought Chad and its neighbours into the fray.
In March, Shekau pledged allegiance to the Islamic State group and its leader Abu Bakr al-Baghdadi, renaming his organisation "Islamic State West Africa Province", or "ISWAP".
Deby's speech on the group's decapitation made headlines around the world, but shed little light on Shekau's putative replacement, an apparently new player in global jihad who was virtually unknown before last week.
Nigerian security analyst Fulan Nasrullah, one of the country's most respected Boko Haram watchers, argues in a blog post for the London-based Royal African Society that the "Mahamat Daoud" to whom Deby referred is actually Muhammad Daud, a Shuwa Arab from Borno State, the cradle of the insurgency.
Daud, aged around 38, is an ex-serviceman and protege of slain Boko Haram founder Muhammad Yusuf, who disagrees with the 2009 uprising and is "one of the few top dogs against the pledge of allegiance made to Islamic State", Nasrullah says.
The militant, who has a Chadian mother, is a powerful commander in charge of counter-intelligence and internal security who oversaw the training of suicide bombers and the planning of attacks in major cities, according to the analyst.
Nasrullah says Daud has broken away from ISWAP with hundreds of fighters, including commanders who are against the IS pledge and disagree with Shekau's "extreme brutality".
- Hatred of Shekau -
Two months ago, he says, they retook Boko Haram's preferred pre-pledge name "Jama'atu Ahlil Sunnah lidda'awati Wal Jihad", or "Group of the People of Sunnah for Preaching and Jihad".
"They have declared Shekau a rebel against the teaching of Muhammad Yusuf, an apostate, a deviant and a religious hypocrite," Nasrullah writes.
Daud, he says, has approached the government to form an alliance to wipe out Shekau's IS franchise in return for an autonomous state in the northeast ruled by Islamic sharia law.
Crucially, Daud would go into any negotiations with Abuja in possession of key secrets about Boko Haram's fundraising, inner structure and even possibly intelligence on how to track down and kill Shekau.
Boko Haram's leader, according to Nasrullah, is now likely to be in the "rifle sights" of the breakaway Daud, whose "hatred of Shekau may very well surpass his hatred for the Nigerian state".
Andrew Noakes, coordinator of the Nigerian Security Network of analysts, cautions against relying on Deby as a credible source on Boko Haram's internal machinations, however.
"We should remember Deby's previous claim to be facilitating negotiations with Boko Haram over the Chibok girls last year, when in fact the interlocutor turned out to be a fake," he told AFP, referring to the kidnapping of more than 200 schoolgirls.
Noakes sees a coup within Boko Haram's ranks as "plausible", however, pointing to numerous potential sources of a schism in the group, including over its failure to hold onto territory.
"If it has happened then it could mean a number of things. According to Deby it may mean negotiations with the government. But it could also mean the group turns inward as a power struggle plays out," he said.