At least 13 Chadian soldiers have been killed in fighting in northern Mali, the heaviest casualties sustained by French-led African troops since the launch of a military campaign against rebels last month, Chad's army has said.
Sixty-five rebel fighters were also killed in the clashes that began before midday on Friday in the Adrar des Ifoghas mountains near the border with Algeria.
"The provisional toll is ... on the enemy's side, five vehicles destroyed and 65 terrorists killed," said a statement from the army general staff read on state radio. "We deplore the deaths of 13 of our valiant soldiers."
Earlier this month, Chad deployed 1,800 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 rebels.
Also on Friday, two suicide car bombers targeted ethnic Tuareg forces in the northern town of Tessalit, killing three people.
"The two [suicide bombers] were killed and in our ranks there were three dead and four seriously wounded," Mohamed Ibrahim Ag Asseleh, a spokesman for the ethnic Tuareg rebel group, the MNLA, in Burkina Faso confirmed.
Tuaregs in the north, who have long sought greater autonomy, rebelled against the federal government and swept across northern Mali in April last year, taking advantage of a power vacuum left by a military coup.
However, the MNLA and other Tuareg groups were sidelined by armed groups such as the Movement for Oneness and Jihad in West Africa (MUJAO), who took over major towns of northern Mali and imposed Islamic law.
The MNLA blamed Friday's car bomb attacks on the MUJAO.
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The MUJAO made no comment on the latest attacks, but on Thursday it said that it was responsible for another car bomb in Kidal.
France intervened in its former West African colony on January 11 to stop a southward offensive by the rebels who seized control of vast swaths of the north in April last year.
Troops from neighbouring African nations - including from Chad - have since deployed to Mali and are set to take over leadership of the operation when French forces begin a planned withdrawal next month.
However, continuing violence since the rebels were driven from major urban areas highlights the risk of French and African forces becoming entangled in a prolonged conflict as they try to help Mali's weak army counter bombings and armed raids.
A US defence official said on Friday that Washington had deployed several Predator drones to Niger to fly surveillance missions in support of French forces in Mali.