Militants killed around ten Malian soldiers on Thursday near the west-central town of Guire, the army said, the deadliest such attack against the armed forces since an 18 August military coup.
International powers fear the ousting of President Ibrahim Boubacar Keita could further destabilise the West African nation and undermine the fight against insurgents linked to al Qaeda and Islamic State in the wider Sahel region.
The latest attack, which targeted a resupplying mission, took place at 6 pm and also caused injuries and material damage, the army said in a statement on Friday.
Reinforcements have been dispatched to the area, it said.
Islamist groups operate in arid central and northern Mali, using the area as a base to attack soldiers and civilians in neighbouring Burkina Faso, Niger and beyond.