Militants in northeast Mali killed 53 soldiers and one civilian in an attack on a military post, the government said.
This makes it one of the deadliest attacks in the last decade.
In a tweet, the army described it as a "terrorist attack".
Mali has been violent since 201
Violence has spread to other countries in the region.
- Why Sahara is the new frontline for terror
No group has claimed to be behind the Indelimane attack in the Menaka area.
Thirty-eight soldiers were killed when two military camps were attacked near the Burkina Faso border in late September.
Mali – along with Burkina Faso, Chad, Niger and Mauritania – is part of an insurgency force backed by France, known as the G5 Sahel.
The Five National Group blamed "suspected members of Islam Ansarul" for the September attack.
Islam Ansarul, meaning defenders of Islam, was created in 2016 by the radical and popular preacher Ibrahim Malam Diko. He reportedly fought Islamist fighters in northern Mali in 2012.