No group claimed immediate responsibility for the bomb, but jihadist violence in Burkina Faso has been blamed on militants linked to both Al-Qaeda and Islamic State groups.

"A homemade bomb killed six soldiers and inured another" during a patrol in a wildlife reserve in Soum province, the army said in a statement.

Earlier, the number of dead had been put at five.

A military sweep of the area was begun following the attack, the military added.

"Reinforcements were sent to the zone to clear the area while the wounded were evacuated," a military source said.

A wave of attacks at December killed 35 civilians, mostly women, and dozens of soldiers in an assault on a military base and a town in the north of the country.

Burkina Faso, as well as neighbouring Mali and Niger, has seen frequent jihadist attacks which have left hundreds of people dead since the start of 2015 when Islamist extremist violence began to spread across the Sahel region.

According to the UN, around 4,000 people were killed in jihadist attacks in the three Sahel countries last year.

The Burkina Faso army is ill-equipped and poorly-trained to deal with the threat posed by jihadists in the country.

However, in recent months they have enjoyed a series of successes, claiming to have killed a hundred jihadists in many operations.

There are 4,500 French troops deployed in the Sahel region as well as a 13,000-strong UN peacekeeping force in Mali to fight insurgents, backing up national forces of the G5 -- Chad, Burkina Faso, Mali, Mauritania and Niger.