Mario Balotelli has been branded "ordinary" and a player who has repeatedly wasted great career opportunities by former team-mate Adel Taarabt.
The accusations came on a day when Inter Milan played down prospects of the striker leaving Liverpool to join them in January.
Inter vice-president Javier Zanetti takes a different view to Taarabt - labelling Balotelli "a great player" - but the Italians believe recruiting the 24-year-old during the winter could be unrealistic.
Balotelli has struggled since moving to Anfield at the end of the summer transfer window and Inter are keen to strengthen their attacking line.
However Zanetti told Sky Italia: "A Balotelli return? We all know Mario is a great player but I think it's difficult because he only just arrived at Liverpool.
"In any case, after our game against Lazio (on December 21) we will hold meetings to see what we can do and what is needed in terms of the (transfer) market."
Balotelli has scored only two goals in his 14 appearances for Liverpool, and QPR playmaker Taarabt, who played with him while on loan at AC Milan last season, does not see the Italy international as a top quality forward.
Speaking to Italian TV channel Sky Italia, Taarabt said: "Balotelli? Everyone told me he was amazing and I played with him and I can say he is strong but he didn't seem to me as though he was world class.
"He is an ordinary player, not a phenomenon."
Taarabt added: "He is someone who has a strong shot but he doesn't play for the team. And if he does, he doesn't score as is the case right now at Liverpool.
"He's had so many chances, from (Manchester) City to Milan, and he's thrown them away."
A return to the San Siro would see Balotelli reunited with Roberto Mancini, who coached Balotelli at Inter and Manchester City.
Mancini, who took the reins at Inter last month for a second spell in charge, revealed after Monday's 2-0 triumph at Chievo that he was keen to bolster his attack.
"In certain roles in attack we are lacking," Mancini told Gazzetta dello Sport. "The club are aware of this but in January it will not be easy."
Balotelli came through the ranks at Inter before being sold to Manchester City in 2010.
He joined Liverpool in a £16million move from AC Milan but as well as lacking form, he has missed a number of games with a groin injury and was recently charged by the Football Association over a controversial posting on Instagram.
Balotelli has accepted the charge in relation to making racist and anti-Semitic comments on social media but has offered mitigation for his actions. He posted an image of computer game character Super Mario on Instagram which included the words ''jumps like a black man and grabs coins like a Jew''.