Chad said Wednesday it inflicted heavy losses on Nigeria's Boko Haram, killing "over 200" Islamist militants in a border town that it wrested from the rebels in a ground offensive.
Nine Chadian soldiers were also killed and 21 injured Tuesday in Gamboru as regional forces took the fight against the insurgents on to Nigerian soil for the first time, the Chadian army said.
Around 2,000 Chadian troops backed by armored vehicles poured across the border into Gamboru Tuesday after the African Union last week backed a regional force to take on the extremists.
The Cameroonian troops had managed to repel the attack by mid-morning, after Chadian soldiers crossed back from Nigeria to help defend the town.
Chadian troops and vehicles have massed near Boko Haram-held towns along Nigeria's border with Niger, pointing the way to another possible cross-border operation.