Forty-two soldiers were killed and 22 injured in an attack near the town of Tessit on Sunday, Mali's government said on Wednesday, blaming an affiliate.
It was one of the deadliest attacks in recent years for the Malian army, which has been battling a decade-long insurgency by militant groups that have spread across West Africa's region.
"The Malian army units of Tessit... reacted vigorously to a complex and coordinated attack by armed terrorist groups, presumably from Islamic State in the Greater Sahara (ISGS), characterised by the use of drones, explosives, car bombs, and artillery," the government said in a statement.
Soldiers killed 37 combatants during several hours of heavy fighting, it added.
The army had previously said that 17 soldiers had been killed in the attack and that nine had gone missing.
Mali is ruled by a military junta that overthrew the democratic government in 2020, in part over frustration at its failure to rein in violence, but attacks have remained common.
An al Qaeda affiliate claimed an attack on the country's main military base in late July.