Many Boko Haram fighters reportedly killed in first action by foreign troops on Nigerian soil against the armed group.
Nigerians who fled from Boko Haram fighters have now become a headache for Chadian authorities after seeking safety across the border.
More than 11,000 people have arrived at a refugee camp in Ngouboua since Boko Haram attacked the town of Baga in northeastern Nigeria on December 3.
The international community has so far remained focused on stopping the Boko Haram fighters, not on how to deal with refugees that have been displaced. Aid workers say a refugee crisis could destabilise the region.
Al Jazeera’s Mohammed Adow reports from N’djamena.