Boko Haram killed at least 18 people and wounded scores in coordinated attacks overnight on a military camp and villages around the flashpoint Nigerian city of Maiduguri, which they also tried to infiltrate across a defensive trench, officials said yesterday.

The brazen operation -- which unfolded around the very city where Boko Haram was born -- turned the spotlight on the authorities' struggle to quell the jihadists' nearly nine-year-old offensive.

Boko Haram fighters attacked a military base in the Cashew Plantation area at the entrance to the city with suicide bombers, mortars and guns, leading to a prolonged battle, a senior military officer in Maiduguri said.

"Eighteen Boko Haram terrorists on foot attacked the military base while seven suicide bombers targeted residents of nearby Bale Shuwar and Alikaranti villages at 8:50 pm (1950 GMT)," said the officer who asked not to be identified because he was not authorised to speak about the incident.

"The terrorists fired mortars at troops," the officer said.

"So far we have recovered 18 dead bodies from the two villages," Bello Dambatto, an official from the State Emergency Management Agency (SEMA) told AFP.

"The victims were killed while trying to escape the fight between the insurgents and the military," said Dambatto.