Chad suffered the heaviest losses so far in the French-led campaign to drive Islamists from northern Mali after a battle in which it said 13 Chadian soldiers and 65 Islamist rebels were killed.
News of the battle came after two suicide car bombers targeted ethnic Tuareg forces in the northern town of Tessalit, killing three people.
A US official meanwhile confirmed that Washington had deployed several Predator drones to Niger to fly surveillance missions in support of French forces in Mali.
The clash between Chadian forces and the Islamists took place in the mountainous Ifoghas region of northern Mali, Chad's military command announced.
"The Chadian army destroyed five vehicles and killed 65 jihadists," the military said in a statement. But 13 of its soldiers had been killed and another five wounded.
Earlier this month Chad deployed 1800 soldiers in the northern city of Kidal to secure what had been the rebels' last urban stronghold, putting itself in the frontline in the fight against the Islamists.
A car bomb attack on Thursday there near a military camp for French and Chadian troops had wounded two civilians.
North of Kidal lie the Ifoghas highlands - to where many of the Islamist forces have withdrawn - and the town of Tessalit.
Two vehicles targeting civilians and members of the ethnic Tuareg rebel group, the MNLA, exploded near the town on Friday, killing three and wounding several others, a security source said.
A spokesman for the National Movement for the Liberation of Azawad (MNLA) in Burkina Faso confirmed the report.
A US defence official, meanwhile, confirmed that drones were now flying out of Niamey, Niger, from a base with a 100-strong contingent of air force personnel.
President Barack Obama had announced on Friday that US troops had been sent there to provide intelligence for the French forces and "other partners" in the region.
France sent in troops on January 11 to help the Malian army oust Islamist militants who last year captured the desert north of the country. Since then, thousands of soldiers from African countries have also been deployed and France plans to start withdrawing its troops next month.
The French-led forces met little resistance during the initial offensive that drove the Islamists from the main northern centres of Gao, Kidal and Timbuktu.
Now however, they are facing a guerrilla campaign that includes sudden raids, suicide attacks and land mines.
The Tuareg MNLA blamed Friday's car bomb attacks on the al-Qaeda-linked Movement for Oneness and Jihad in West Africa (MUJAO), one of Mali's main Islamist groups.
The MUJAO made no comment on the latest attacks, but on Thursday it told AFP it was responsible for the car bomb in Kidal. MUJAO spokesman Abu Walid Sahraoui warned of more such attacks.
Sahraoui also said they had sent fighters to another northern town, Gao, 1200km from the capital Bamako and that they were determined to recapture it.