Borno state’s commissioner for works, Yerima Saleh, confirmed the incident and said three vehicles, including a Toyota Hilux and two tippers, were also seized by the militants.

Mr Saleh added that the victims were en route to inspect a road project near Chibok town.

Damboa and Chibok towns are close to Sambisa forest, which is the main hideout for militants in the region.

Borno is among three north-eastern Nigeria states that have endured a protracted jihadist insurgency that has killed hundreds of thousands and displaced millions of people.