"A forward security forces position, composed mainly of auxiliaries from the Volunteers for the Defence of the Fatherland (VDP), was targeted by armed terrorist groups," said one official, using the army's term for jihadists.

"Unfortunately five people, all volunteers, were killed," he told AFP of Thursday's incident in the Gnangdin area, near the border with Togo and Ghana.

The volunteers, who work with the army, are recruited locally, given weapons and three months' training.

They may operate with professional soldiers or on their own.

The incident triggered a protest among locals who blocked the main highway linking the region to the Togolese border, a local inhabitant told AFP on condition of anonymity.

The blockade continued for several hours before the authorities broke it up, he said.

"There is a (military) unit in the area but it took them a while to react, which shouldn't have happened. If groups can still carry out attacks despite the presence of this unit, then there's still work to do," he said.

Jihadist violence erupted in neighbouring Mali in 2012 and then spread to Niger and Burkina.

All three west African countries are run by military juntas.

Since the unrest spread to Burkina Faso in 2015, it has killed around 26,000 people and forced some two million people to flee their homes, according to monitoring group ACLED.