At least four Cameroonian soldiers, including a general who was coordinating the fight against Nigerian Boko Haram militant Islamists, were killed yesterday in a helicopter crash.

"We lost four men, including the general", named as Jacob Kodji, as well as a colonel, a senior military official who is involved in the fight against Boko Haram, said.

The men were killed when the Cameroonian military helicopter they were travelling in crashed in Bogo region in the far north, said the official, without giving details of the cause of the accident.

"They were on a mission in Waza Park as part of an operation to battle Boko Haram," the military official added.

Ceoafrica gathered that General Kodji was the leader of Emergence 4, the name given to one of the operations launched by Cameroon against Boko Haram insurgents.

He is the first Cameroonian general to die in the battle against Boko Haram, whose insurgency has spread across the border into Cameroon, Chad and Niger as the militants have been pushed out of their strongholds in north-eastern Nigeria.

At least 20,000 people have been killed and some 2.6 million displaced in the violence.