The previous official toll from Friday's twin assault on the country's military headquarters and the French embassy had been seven soldiers and nine attackers dead, and there was no mention of any civilian casualties.
"The confusion (over the number of dead) stemmed from a body that was found on the site" of the attacks, public prosecutor Faso Maiza Sereme told a press conference.
"After further tests and checks, it proved to be one of our soldiers," she said.
Eight people have been arrested, including two soldiers and a former soldier who had been thrown out of the armed forces, Sereme said.
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"Complicity cannot be ruled out" in the attack against the military HQ, she said. Other sources have previously suggested that the attackers had had inside information from within the armed forces.
Government and security sources, speaking in the wake of the attack, said two men were in custody, one of whom could be a mastermind of the operation, which has been claimed by a jihadist group called the Group to Support Islam and Muslims (GSIM).
She said the first attack took place outside the French embassy at 10 am when three men travelling in a car whipped out Kalashnikov assault rifles and opened fire, killing a Burkinabe security guard stationed outside the building.
However, they failed to enter the complex.
Minutes later, four others -- two travelling on a motorbike and the two others in a car -- attacked the army headquarters with Kalashnikovs and grenades.
The attack on the military headquarters, said sources, appears to have been aimed at a scheduled meeting of the so-called G5 Sahel -- a French-backed group of five countries fighting jihadism in the volatile Saharan region.
The room in the complex where the meeting was to have taken place was wrecked by the car bomb -- however, the venue was swapped at the last minute, which prevented carnage.
GSIM said the attack was a response to the deaths of some of its leaders in a French army raid in northern Mali in February in which 20 jihadists were either killed or captured, according to French military sources.
He told the French parliament's foreign affairs committee he would "show our solidarity with the embassy personnel and the Burkinabe forces".
Le Drian will also visit neighbouring Niger, along with French Interior Minister Gerard Collomb, to identify people who deserve asylum in France from a list drawn up by the UN's refugee agency.