A military strike on a Boko Haram camp in Nigeria's restive northeast last week left about 150 Islamists and 16 soldiers dead, the army said Wednesday, amid reports of dozens of troops killed.
The army's claim of a major offensive against the Islamist insurgents on September 12 came after local media reported that Boko Haram had ambushed a group of soldiers in the same area, killing 40 and leaving dozens of others missing.
Military officials were not available to comment on the reported Boko Haram ambush, speaking only about the purported military strike.
Details of last week's military operation had not been previously made public.
"It was a highly fortified insurgent camp with heavy weapons in (northeastern) Borno State," army spokesman Ibrahim Attahiru said, adding that the camp was in the Kasiya forest.
"The army raided the camp on September 12. Some 150 Boko Haram terrorists were killed, while the military lost 16 soldiers. Nine soldiers are still missing," he told AFP.
The forest where the alleged raid occurred is some 70 kilometres (43 miles) northeast of Borno's capital Maiduguri, the city where Boko Haram was founded more than a decade ago.
The area surrounding Kasiya had acquired a reputation for armed robbery.
There has been speculation that Boko Haram had strengthened its presence in the remote area in recent months, several people familiar with the region told AFP.
Borno was placed under a state of emergency in mid-May, when the military shut down the mobile phone network to block Islamists from coordinating attacks amid an operation aimed at crushing the insurgency.
With the communication network switched off, details of attacks have been slow to emerge and difficult to verify.
Residents, victims as well as local political leaders have been largely unreachable, with military statements forming the main source of information in the ongoing offensive against Boko Haram.
The military has claimed major successes in the operation, describing the insurgents as being in disarray.
There are indications that Boko Haram attacks, which were previously carried out across northern Nigeria, have been partly contained in the northeast, especially Borno state, the group's historic stronghold.
If confirmed however, Boko Haram's reported ambush on the military would cast doubt on claims that the insurgents' capacity to attack has been curbed.
According to local media, the alleged Boko Haram ambush happened in the northeastern corner of Borno state, towards the border with Chad.
Widely read Punch newspaper, citing a high-ranking military source, said the military failed to send aerial support for the soldiers who were ambushed.
According to the paper, the failure to send air support has led to anger among soldiers involved in the pursuit of Boko Haram.
Since the offensive was launched, Boko Haram has been blamed for massacres that left dozens of students of dead, as well as the mass killing of Muslims gathering for morning prayers, among other attacks.
The Islamists have also repeatedly clashed with vigilante groups which have formed in Borno.
Boko Haram has said it is fighting to create an Islamic state in northern Nigeria, but its aims have shifted and the group is believed to consist of different factions.
Nigeria is Africa's most populous nation and top oil producer, with a mostly Christian south and a predominately Muslim north.