Gazzetta dello Sport says City manager Roberto Mancini and assistant Attilio Lombardo had talks with Romanian Marin during the recent youth tournaments in Gubbio and Chianciano.
"We don't know anything official yet, but it's clear the lad will no longer be playing with us," slammed director of sport Igli Tare.
"He can go to City. Mancini acted dishonestly. He could've made a phone call and told us. That's no way to behave.
"In theory we could've signed Marin, but in practical terms we couldn't, because we would've had to do the same with another 10 teenagers in our academy. That would've wrecked the budget.
"The truth is that the current rules on young players in Italy have to be changed."