The French military responded to a request from former colony Mali to help address a threat from foreign rebels and al-Qaida fighters who seized territory following an early 2012 coup.
A European training mission, led by French Brig. Gen. Francois Lecointre, said trainers should be in Mali for more than a year.
"Objectively, (the army) must be entirely rebuilt," he was quoted by the BBC as saying. "The Malian authorities are well aware of the need to reconstruct the army, very aware that Mali almost disappeared due to the failings of the institution."
Rights groups have expressed concern that Malian forces may seek revenge on ethnic populations in north Mali that are seen as supporting militant forces.
The French government said most of its combat forces should be out of Mali by July. U.N. Secretary-General Ban Ki-moon last month called for an African force to integrate into a U.N. mission that would replace French forces.
Fighting continues in the rebel-held north.