A local prosecutor in Burkina Faso has launched an inquiry after 12 people detained on suspicion of terrorism were found dead in their police cells on the same night.
The victims were reported to be among 25 suspects from the ethnic Fula community who were being held in the town of Fada N’Gourma.
The case comes weeks after advocacy group Human Rights Watch accused Burkina Faso security forces of executing 31 unarmed detainees during operations against Islamist militants.
Burkina Faso has been battling armed Islamist insurgents, some with ties to al Qaeda and Islamic State, since 2017.
The militants have strengthened their foothold in the northeast and eastern parts of the country around the tri-border region with Niger and Mali.
HWR said in April the militants have killed more than 300 civilians in Burkina Faso, while the government has killed several hundred men for their alleged support of the groups.