Boko Haram chief 'badly wounded': What we know

In the 12 years since Nigeria's jihadist insurgency erupted in the northeast, Boko Haram leader Abubakar Shekau has been reported dead several times, only to reappear unscathed.

On Wednesday, intelligence sources say, rival Islamic State-allied jihadists attacked Shekau's faction in their stronghold in Sambisa forest in northeast Borno state.

Shekau was seriously wounded after trying to kill himself to evade the IS jihadists who surrounded him following a series of battles, the sources said.

Nigerian media has been filled with speculation that the man who made international headlines for kidnapping nearly 300 schoolgirls in 2014 might finally be dead.

But 24 hours after the news broke, the army was still investigating and details about where Shekau may be remain unclear.

Here is what we know.

Dead or wounded?

If sources are unclear about whether Shekau survived, it is not the first time. The jihadist commander has resurfaced after multiple reports of his death over the years.

"The whereabouts of Shekau and his fate are still a subject of speculation," an intelligence source said on Friday after the Sambisa attack.

"Only his close allies can give definite information on his state, whether he is dead or battling for his life."

The Nigerian army spokesman could not confirm any of the details and said an investigation was still ongoing.

Neither Islamic State in West Africa Province (ISWAP) or Boko Haram have released any communique about the attack on Sambisa or the whereabouts of Shekau.

Jihadists have a policy of avoiding power vacuum by appointing a successor once a leader dies or is removed.

"The fact that Boko Haram has not named Shekau's successor is a strong indication he is not dead yet," one of the sources said.

Who are the factions?

More than 40,000 people have been killed and over two million displaced from their homes by the conflict in northeast Nigeria since 2009, and fighting has spread to parts of neighbouring Chad, Cameroon and Niger.

Since 2016, two rival factions emerged from Boko Haram after disagreements over Shekau's indiscriminate attacks on Muslim civilians and use of children and women as suicide bombers.

Shekau's Boko Haram faction, known formally as Jama'tu Ahlis Sunna Lidda'awati wal-Jihad or JAS, was based in the Sambisa forest, and in the far northern border of neighbouring Cameroon as well as Chad and Niger.

The other was Islamic State in West Africa Province or ISWAP with its stronghold in Alagarno forest and areas of Lake Chad.

Sporadic clashes have erupted between the two factions over influence and territory.

According to local intelligence sources, a new round of fighting erupted in April during the Muslim holy month of Ramadan.

Boko Haram fighters ambushed an ISWAP brigade as they transported weapons to one of their main camps, sources said. Several ISWAP men were killed.

In retaliation, in May, ISWAP launched an attack on a Boko Haram camp. Both sides suffered losses. But, the sources said, ISWAP took the fight to Boko Haram directly in Sambisa forest further south.

"ISWAP's invasion of Sambisa was not to make Shekau surrender but to kill him for his unprovoked attack on its fighters in recent weeks," one local intelligence source said.

What happened in Sambisa?

According to details from the two intelligence sources, a large convoy of ISWAP trucks mounted with machine guns entered Sambisa.

One group headed to the Boko Haram camp in Sabilul Huda, where Shekau had sought refuge. His faction had recently been weakened by air strikes by the military.

ISWAP fighters surrounded the house where Shekau had been holed up, the sources said.

What happened next is not fully clear, but Shekau was seriously wounded when he tried to kill himself to avoid being taken.

Intelligence sources said Shekau shot himself in the chest and was later rescued unconscious by some of his men and taken to an unknown location.

What happens next?

Whether he is seriously wounded or dead, the loss of Shekau would be a huge blow to his Boko Haram faction where he was a central figure for years, analysts said.

ISWAP had already became the more dominant force in Nigeria's northeast showing its capacity to carry out complex attacks on the armed forces.

Its fighters have recently overrun several army bases.

Taking Shekau's Sambisa forest stronghold would allow ISWAP to consolidate territory it already holds in Alagarno forest and southern Lake Chad, potentially allowing the group to control roads leading to the Borno state capital Maiduguri.

While some pro-Shekau brigades along the Cameroon border and in Niger and Chad may want autonomy, ISWAP may now access a pool of Shekau's fighters and a partial reunification may be in the works, said Vincent Foucher, a fellow at French National Centre for Science Research.

"Surely it is under discussion, all these guys are connected, they know each other and there must be negotiations going on. There are still some unknowns but what is clear is that it is a big win for ISWAP," he said.

"A lot of people are happy to see Shekau dead, but it is not very good news if ISWAP becomes the single jihadist force in the area."