Nigeria's army has announced a major overhaul of its leadership in the fight against Islamist militant group, Boko Haram.

The move comes after a wave of attacks against military convoys and barracks in recent weeks.

The most significant appointment is that of Maj Gen AM Dikko who has been made the new commander of Operation Lafiya Dole, the military’s initiative to defeat the militant group.

He is the fourth commander of the task force in a little over a year.

In a statement, an army spokesperson said the appointment of Gen Dikko was to inject new blood to "further actualise the vision of the Chief of Army Staff".

But it comes shortly after a series of attacks by Boko Haram militants on the army, including on a barrack in Yobe state where dozens of soldiers are believed to have been killed.

The army denies it suffered any casualties in the attack.