Army Suspected Boko Haram insurgents have killed more than 44 army officers, including a senior commander, in an attack on a military base in a remote village in north-eastern Nigeria, according to army sources and local media.
Driving in a convoy of gun-mounted trucks, the militants overrun the base in Maitele in Borno state near the border with Niger, they said.
Many other soldiers are reportedly missing following the attack on Sunday.
The attackers have also seized military equipment.
In a separate assault on Tuesday, reports say the militants killed at least nine civilians and abducted more than a dozen others in the village of Mammanti also in Borno state.
The Nigerian army has not officially confirmed nor denied the reports.
Boko Haram and its splinter faction known as Islamic State West Africa Province (Iswap) have stepped up deadly attacks in recent months on military and civilian targets in the region.
This comes as Nigeria prepares for presidential and parliamentary elections in February.