Heavily armed "terrorists" ambushed a convoy of elite rapid intervention forces at Bamessing in the Northwest Region on September 16, the ministry statement said.

"Using IED (improvised explosive devices) and an anti-tank rocket launcher, the insurgents immobilised the vehicles (in the convoy) before opening heavy fire on the latter," it added.

Another IED hit a military convoy at Kumbo, in the same region, on September 12.

The ministry estimated the total death toll at "about 15 soldiers and several civilians".

Western Cameroon is in the grip of a four year conflict triggered by militants demanding independence for two predominantly English-speaking regions in the francophone-majority state.

More than 3,500 people have been killed and over 700,000 have fled their homes.

Rights groups say abuses have been committed by both separatists and the armed forces.

The defence ministry noted "the existence of links and exchanges of sophisticated weaponry" between "secessionist terrorists" and "other terrorist entities operating beyond the borders", including fundamentalist groups.