Two Malian soldiers were killed and four wounded in an ambush on their convoy near the central town of Nampala on Saturday, military sources said.
Armed men placed explosives on a road in a region near the Mauritanian border where Islamist militants have launched attacks in the past, the sources said.
The attackers set off the devices "to stop the convoy and then opened fire at our men," one officer in the nearby town of Mopti told Reuters by telephone on Sunday.
A senior military official in the capital Bamako said reinforcements have been sent to the region.
Mali's desert north is home to a number of armed groups as well as al-Qaeda-linked Islamist militants that briefly held the area until they were scattered by a French military intervention in 2013.
However, insecurity persists and attacks have crept further south in recent months.
Malian authorities have blamed a recently emerged armed group called the Massina Liberation Front, made up of fighters from the Peuhl group, for the growing number of attacks in the central Mopti region.
