Christians are among the 150 people killed in "unprecedented" attack by Islamist terrorists in Burkina Faso. 

The attack happened last Friday when soldiers and civilians were digging defensive trenches to protect themselves in Barsalogho, central Burkina Faso, according to reports received by Catholic charity Aid to the Church in Need (ACN).

Twenty-two Christians were among the victims of what ACN described as one of the deadliest atrocities in Burkina Faso's history. 

Bishop Théophile Nare of Kaya called it a "tragedy of unprecedented proportions" and announced Wednesday as a day of mourning for the victims, who also included children. 

"I make it my duty to come and urge you not to let yourselves be defeated but to keep hope, which is hope that keeps us alive," he said. 

"I would also like to exhort you to penance and conversion so that the God of mercy can give us the healing and consolation that we expect from him."

Burkina Faso has struggled to contain the spread of Islamist extremism in the last decade and violence has continued this year with three attacks this month alone. 

The whereabouts of over a hundred people kidnapped by gunmen at the start of the month remains unknown. They were taken in the Boucle du Mouhoun region of western Burkina Faso.