The striker was not involved in City's FA Cup win over Stoke on Saturday, fuelling more speculation over the Italy international's long-term future at the Etihad Stadium.
City manager Roberto Mancini insisted on Friday that Balotelli was staying at the club despite being continually linked with a move to AC Milan.
However, Milan vice-president Adriano Galliani has left the door open for a possible move for Balotelli after ruling out deals for Real Madrid's Kaka and Didier Drogba.
"Kaka and Drogba are 101% not coming to Milan. Balotelli? He is 99.9%..." Galliani told milannews.it
It has been suggested Milan would like to sign Balotelli on loan, but the player's agent Mino Raiola has revealed City's hierarchy have ruled out the possibility of a temporary switch.
"The truth about Mario? You have to ask to others, because I cannot say it," Raiola told Radio Deejay.
"Until January 31, anything can happen, we are monitoring. We have not talked about money because there is nothing concrete yet.
"But I can rule out the loan, the City directors do not accept this solution. Also because they received a €40million (£34m) offer for Mario during the European Championship."