The former Chelsea defender says that the Italy forward is "unmanageable" and has advised the Rossoneri to offload him sooner rather than later.
Balotelli put in a strong performance for the San Siro side in its 1-0 Champions League defeat against Atletico Madrid on Wednesday, but had to be taken off in the closing stages of the second half after picking up a shoulder injury and Leboeuf was not impressed by the striker's behavior after his substitution.
"Balotelli is unmanageable. He is the type of person who is poison to the team," Leboeuf told RMC. "I saw him play against Atletico Madrid and he disrespected Clarence Seedorf's authority. He did not want to come off after injuring his shoulder.
"Seedorf nearly had to shout in order to get him substituted. There's no denying that he has a lot of talent, but it impossible to use him as he simply does not fit in. This is a real shame for Italy because they have a great national team."
Balotelli has been a key figure for Milan this season, scoring 14 goals in 28 appearances in all competitions.