Thirteen Chadian soldiers and 65 Islamist insurgents have been killed in heavy fighting in a remote part of northern Mali, Chad's military says, reports the BBC.
It says Friday's clashes occurred in the Ifoghas mountains, where many militants are believed to be hiding.
Last month France led an operation to help oust Islamists who seized the vast northern region of Mali in 2012.
The US military says it has deployed surveillance drones in Niger to gather information on the Islamist militants.
The intelligence collected by a 100-strong contingent of US personnel from across the border is being shared with French troops in Mali, who are assisting thousands of troops from African states.
Islamist rebels are believed to have retreated to the Ifoghas mountains - a desert area in the Kidal region near the border with Algeria - after being forced from northern population centres in recent weeks.
In a statement issued late on Friday, the Chadian army said it had "destroyed five vehicles and killed 65 jihadists", adding that 13 of its soldiers had been killed and another five wounded.
Earlier this month, some 1,800 Chadian soldiers began patrolling the city of Kidal.
Read more of this report from the BBC.