Fighters from the Islamic State West Africa Province (ISWAP) opened fire on the convoy in Barwanti village in the Lake Chad area late Friday, after a landmine they had planted exploded under one of its trucks.

"The terrorists opened fire, killing three soldiers and seizing a gun truck," one officer told AFP.

"Two soldiers remain missing while one was seriously injured," he added.

A second military source confirmed the toll.

The convoy was heading to the fishing town of Baga on the shores of Lake Chad, ISWAP's major stronghold when it was ambushed.

The jihadist groups Boko Haram and ISWAP are both very active in Nigeria's northeast.

Since the start of their uprising in 2009, they have killed at least 36,000 people in the region and forced two million people to flee their homes.