Thirteen soldiers from Chad and 65 Islamist insurgents have been killed in heavy fighting in a remote part of northern Mali.
Chad's military says the clashes happened 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 rebels are believed to have retreated to a desert area in the Kidal region near the border with Algeria after being forced from northern towns and cities.
Thousands of soldiers from African countries have also been deployed in Mali since then, including 1,800 Chadian soldiers patrolling the city of Kidal.
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.
Fighting between Islamist insurgents and Malian troops - backed by French soldiers - also continued in the central city of Gao.
On Thursday, the coalition said it had recaptured the city hall, which had been seized by militants a day earlier.
In a separate development, the United States military said it had deployed surveillance drones in Niger to gather information on Islamist militants across the border in Mali and share intelligence with French troops.
The US said a 100-strong contingent was operating the drones out of a base in Niger.
France intervened in January in its former colony, fearing that al-Qaeda-linked militants who had controlled Mali's north since April 2012 were about to advance on the capital Bamako.
The French have said they are planning to start withdrawing their 4,000 soldiers next month, and would like the African-led contingent to become a UN peacekeeping operation.