Around 170 people were "executed" in attacks on three villages in northern Burkina Faso a week ago, a regional public prosecutor said in a statement on Sunday.
Aly Benjamin Coulibaly said the attacks were carried out on Komsilga, Nodin and Soroe villages in Yatenga province on February 25, with a provisional toll of "around 170 people executed".
An investigation had been launched into the attacks by unknown assailants, he added.
The West African Sahel nation has been struggling to contain violent insurgencies that have spread from neighbouring Mali over the past decade, killing thousands and displacing more than two million.
Last week, an attack on a mosque in eastern Burkina Faso left dozens of Muslims dead on the same day another deadly attack was carried out on Catholics attending mass.
