Tevez travelled to his native country on Monday night to see his family and, while Tuesday was a scheduled day off for the 27-year-old, he was due at City's Carrington training ground on Wednesday morning - but did not show up.
A spokesman for Tevez told Press Association Sport: "He tried countless times to speak to Roberto Mancini."
The club have stressed that it had been made clear to Tevez that he would be required to come in, but it seems the striker believes he made every effort to seek permission for his journey home.
Tevez's spokesman added: "He was told it was Mancini's decision as to whether or not he could go and left numerous voice messages and texts on Mancini's phone.
"He didn't receive a response at all. He then flew to Argentina and tried to speak to Mancini again yesterday (Tuesday), leaving messages and texts. As of this moment we've had no response."
The spokesman was not prepared to comment on when Tevez is likely to return from South America, and City are not yet able to say what punishment the player may face. The news comes just 24 hours after it emerged that Tevez would not be appealing against the club's ruling that he was guilty of misconduct in the Champions League defeat to Bayern Munich on September 27.
City last month fined Tevez four weeks' wages and suspended him for two weeks - deemed to have already been served - after a disciplinary panel found the former Manchester United man guilty of five breaches of contract relating to his behaviour on the bench during the 2-0 loss at the Allianz Arena.
The Professional Footballers' Association become involved, making an intervention that saw the fine cut to two weeks' wages, and having backed Tevez on that occasion, PFA chief executive Gordon Taylor has today expressed his dismay at the fresh turn of events.
"To say the least, I am very disappointed and extremely concerned now,"' Taylor told Sky Sports News.
Source: PA
Source: PA