File photo: Burkina Faso soldiers are seen deployed on September 30, 2022 in Ouagadougou, Burkina Faso. AFP
A detachment of soldiers and the civilian volunteers "was the target of an attack by unidentified armed men on Saturday ... at about 4:00 pm," near Aorema village, the Ouahigouya governorate said in a statement.
The provisional death toll was 34 auxiliaries from the Volunteers for the Defence of the Fatherland (VDP) and six soldiers, the statement said, adding that 33 more people were wounded and in a "stable condition" in the regional capital Ouahigouya's university hospital.
A security source confirmed the death toll and said "several dozen terrorists had been neutralised", meaning killed, during a "riposte" launched after the attack.
Another security source said the detachment that came under assault was deployed to maintain security at Ouahigouya's aerodrome.
"Violent clashes took place yesterday evening ... for nearly two hours," a villager who witnessed the fighting told AFP, asking not to be named.
"Several air strikes had targeted suspected positions held by the jihadists," on Friday, the villager added.
Burkina Faso's military junta had declared Thursday a "general mobilisation" to give the state "all necessary means" to combat a string of bloody attacks blamed on jihadists affiliated with Al-Qaeda and the Islamic State group.
- State of emergency -
Details of the plan were not disclosed, though a security source told AFP it would include "a state of emergency for the affected territories".
Authorities also issued an "advisory" that gives the president "the right to requisition people, goods and services and the right to restrain certain civil liberties", according to another security source.
On Tuesday, the defence minister called for current and retired military personnel to hand in unused uniforms to help outfit army soldiers.
Last week, 44 civilians were reported killed by "armed terrorist groups" in two villages in the northeast, near the Niger border.
It was one of the deadliest attacks against civilians since Captain Ibrahim Traore came to power last September, after 51 soldiers were killed in February at Deou, in the far north.
The government had already announced the same month a plan to recruit 5,000 more soldiers to battle the insurgency that has gripped one of the world's poorest countries since 2015.
Traore, Burkina's transitional president, has declared a goal of recapturing the 40 percent of the country's territory which is controlled by jihadists.
The violence has left more than 10,000 people dead, according to non-governmental aid groups, and displaced two million people from their homes.