The operation in the district of Akabar, a remote part of a game reserve near the border with Niger and not far from the Malian city of Menaka, was continuing, army spokesman Colonel Diarran Kone said by telephone.
“But I can tell you that 20 terrorists have been neutralized,” he said, according to Reuters.
Mali has become increasingly engulfed in violence since a Tuareg uprising in 2012 was hijacked by extremist militants, prompting France to intervene to push them back the following year.
Several extremist factions and allied criminal gangs have regrouped and set up operations in parts of Mali, from where they have launched attacks across the Sahel.
They also now have a significant presence in swathes of neighbor Burkina Faso, and in some remote parts of Niger.
Despite the deployment of 4,500 French troops meant to contain the violence in the Sahel, it has steadily worsened, and the extremists have succeeded in triggering an ethnic conflict.
Attackers believed to belong to the Fulani ethnic group raided the ethnic Dogon village of Sobane Da last Sunday and Monday, killing 35 people, according to the government, although a local authority maintains the real figure is 95 deaths. A bigger massacre by Dogon hunters in March left 150 dead.
Malians have become increasingly frustrated by the failure of the authorities to end regular attacks by extremist groups with links to al Qaeda and Daesh, as well as increasing tit-for-tat ethnic killing between Fulani and Dogon villagers.