At least seven Nigerian soldiers were killed after a mine exploded on a highway in Borno state, the hotbed of a Boko Haram militant insurgency, two vigilante officers said on Friday.

Nigeria faces a raft of security challenges including a long-running Islamist insurgency in the northeast, separatist violence in the southeast, rampant oil theft in the Niger Delta and kidnapping for ransom by criminal gangs.

Shaibu Musa, a local vigilante officer helping to combat the insurgents, said a military vehicle was travelling along the road linking the villages of Monguno and Baga on Thursday when the vehicle detonated an improvised explosive device.

The military did not immediately respond to request for comment on the incident.

Another security official, Isa Bukar, said the explosion occurred on Thursday morning after soldiers on patrol triggered the mine, which killed seven of them.

Reuters