The Boko Haram jihadist group on Thursday claimed responsibility for a rocket attack earlier in the week on Nigeria's northeastern city of Maiduguri that left 16 dead and dozens injured.
In a six-minute propaganda video released on Thursday, a voice claiming to be the group's leader Abubakar Shekau spoke over footage of militants firing rockets outside the city.
"We heard that our brothers carried out an attack on Tuesday in Maiduguri," the voice said.
"We are happy. News has reached me our boys carried out the attack."
Officials said previously that 10 people were killed and 47 were injured when insurgents fired rocket-propelled grenades on the densely-populated capital of Borno state on Tuesday.
Two self-defence militia leaders told AFP on Wednesday that the death toll had risen to 16, including nine boys who were playing football in a field.
Eyewitnesses said the jihadists crossed the ditch fortification around Maiduguri, accessing the city's outskirts from where they fired rockets into busy neighbourhoods.
Boko Haram has previously made incursions into Maiduguri, one of the last secure strongholds in Borno State, using heavy guns and suicide bombers.
Such attacks are usually foiled in fierce gun battles with Nigerian troops.
Since the Islamist insurgency erupted in 2009, the conflict has killed 36,000 people in the region and displaced around two million from their homes.
The violence has spread to neighbouring Niger, Chad and Cameroon, prompting a regional military coalition to fight the insurgents.
The Islamic State West Africa Province (ISWAP) split from Boko Haram in 2016 and has since become a prominent threat, attacking soldiers and bases while killing and kidnapping passengers at fake checkpoints.
Nigeria's President Muhammadu Buhari appointed new military commanders last month after mounting pressure -- even from some allies -- in a bid to breathe new life into the armed forces.