Nigeria's Boko Haram crisis: Bama attack mars victory claims
Suicide bombers are believed to have taken part in a major attack on the northern Nigerian border town of Bama, the army has said.
The attack comes a day after a presidential spokesman said the army was "winning the war" against Islamist militants from the Boko Haram group.
Borno state senator Ahmed Zanna told the BBC the attack on Bama had lasted for five hours on Wednesday morning.
More than 245 people have been killed this year alone by suspected Islamists.
Boko Haram has killed thousands, including many Muslims and Christians, since it began its uprising in 2009.
Defence spokesman Chris Olukolade told the AFP news agency that the Bama assailants had used bombs and had attacked an army tank.
He said "many" insurgents had been killed but did not comment on civilians or military casualties.
The mobile phone network has been severely affected by the Boko Haram insurgency and it has been difficult to contact Bama to get further details.
The town has been attacked several times in the past.
On Tuesday, spokesman Doyin Okupe said the military was "on top of the situation".
Mr Okupe's statement contradicted the comments of the governor of Borno state, where Boko Haram was founded.
Governor Kashim Shettima called for reinforcements and said the insurgents were "better armed and better motivated" than the security forces.
A state of emergency was declared in Borno and two neighbouring states last year, with thousands of extra troops sent to the region, but the attacks have continued.
The BBC's Will Ross in Nigeria says the army has at times taken hours to respond to attacks, allowing the militants to kill, destroy homes, schools and mosques, and loot before retreating.
On Saturday, 106 people were killed in an attack on the village of Izghe.
After meeting President Goodluck Jonathan, Mr Shettima told the BBC Hausa service that without reinforcements "it is absolutely impossible for us to defeat Boko Haram".
But this was denied by Mr Okupe, who said Nigeria's army was one of the best equipped in Africa.
"We state authoritatively without any fear or equivocation whatsoever that Nigeria is already winning the war against terror and the activities of the insurgents will be terminated within the shortest possible time."