The leader of militant Islamist sect Boko Haram, Abubakar Shekau, may have died of gunshot wounds some weeks after a clash with soldiers, the Nigerian military said on Monday.
Past reports of Shekau's death have proved false and there was no independent confirmation of the army account.
In a statement, the army said that Shekau, blamed for a campaign of deadly attacks on security targets and churches across Africa's biggest oil-producing country, was hit during a gunbattle near one of his camps in the northeast on June 30.
He was then taken over the border into Cameroon where he was believed to have died between July 25 and August 3, according to the report issued by the military base in the northeast city of Maiduguri.
Intelligence reports "revealed that Abubakur Shekau, the most dreaded and wanted Boko Haram terrorist leader, may have died," the statement read.
Boko Haram wants to impose Islamic law in Nigeria's north, and, alongside other spin-off Islamist groups, has become the biggest threat to stability in Nigeria.
Though the death of Shekau would be a blow to Boko Haram's campaign, the group has several factions without one homogeneous leadership structure. Spin-off groups like al Qaeda-linked Ansaru, which has claimed responsibility for kidnapping and killing Westerners, are believed to operate independently.
Shekau assumed the leadership of Boko Haram when its founder Mohammed Yusuf was killed in police custody during a crackdown in 2009. Since he took command the group's insurgency has intensified, killing thousands in the last two years.
He is the only high-profile member of Boko Haram, appearing in several videos posted on the Internet where, wagging his finger, he has sworn to bring down the government of President Goodluck Jonathan and criticized the United States for its treatment of Muslims.
The United States, concerned that West Africa could become the next main springboard for international Islamist militant attacks, has offered a reward of $7 million for information leading to Shekau's capture.
Shekau's last public contact was thought to be in a video distributed to journalists in Maiduguri on August 13. Though the video looked and sounded like the same person in previous recordings, the military said on Monday it was a fake.
"The recent video ... was dramatized by an impostor to hoodwink the sect members to continue with the terrorism and to deceive the undiscerning minds," its statement said.