At least 37 people have been killed and 60 wounded in an attack on a mining company convoy in Burkina Faso, authorities say.

Five buses carrying staff of Canadian firm Semafo were ambushed on Wednesday about 40km (24 miles) from the eastern town of Boungou, reports say.

A military escort vehicle was reportedly struck by an explosive device before gunmen opened fire.

It is said to be the third deadliest attack on Semafo staff in 15 months.

Burkina Faso has been wracked by an Islamist insurgency that has killed hundreds of people in recent years.

The military has struggled to contain violence that spilled over the border from neighbouring Mali.