Boko Haram jihadist carried out their deadliest attack on the Chadian army on Friday, killing at least 23 soldiers.
The attack happened at Dangdala near Lake Chad shortly after midnight.
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Security sources said the militants were believed to have crossed over from Niger and made off with military equipment.
Around 30,000 people have been killed and another 2 million displaced since Boko Haram launched an insurgency in Nigeria nearly 10 years ago. It has since spread into neighboring Niger, Chad and Cameroon.
Chad is part of the five-nation Sahel Force established in 2017 to combat jihadist groups and human trafficking.
cw/msh (AFP, Reuters)