A man claiming to be the leader of Nigerian Islamist extremist group Boko Haram has appeared in a video taunting world leaders after the military said he may have been killed.
A security task force in Nigeria said last month that Boko Haram leader Abubakar Shekau "may have died" from a gunshot wound after a clash with soldiers on June 30.
In a video seen by AFP on Wednesday, a man resembling past images of Shekau declares himself to be the extremist leader on whom the United States has placed a $US7 million ($A7.50 million) bounty.
"Here is Shekau, Shekau, Shekau, Shekau, original ... I want the whole world to know that I'm alive by the grace of Allah," he says.
In the video he taunts world leaders, saying they will be disappointed that he is still alive.
Sitting on the ground with an AK-47 leaning against his shoulder, he names Nigerian President Goodluck Jonathan, US President Barack Obama, French President Francois Hollande and Israeli Prime Minister Benjamin Netanyahu as well as Britain's Queen Elizabeth.
It was not clear when or where the video was recorded, but Shekau, speaking in the Hausa language, references recent attacks in northeastern Nigeria, denounces democracy and pledges to keep fighting.
Nigeria's military has not yet responded to the new video, but last month, national defence spokesman Chris Olukolade distanced himself from the claim that Shekau may have been killed.
The video comes after an outburst of violence in northeastern Nigeria in recent days, leaving scores of people dead.
The insurgents say they are fighting to create an Islamic state in Nigeria's mainly Muslim north, but their aims have repeatedly shifted and much of their recent violence has targeted civilians.
