City have been reported to Fifa over the alleged poaching of French kid Jeremy Helan, who was signed by the club earlier this year.
“Manchester City must now realise the consequences of their attitude in the Helan case as it is even more illegal than Kakuta,” Rennes technical director Pierre Dreossi told The Independent.
“We have referred this to Fifa. For us it was strange to have no discussion from City and now, in the week after the Fifa declaration on Chelsea, I would hope that it will be the same thing for Manchester City.
“Kakuta signed up for just a possibility of a full contract. For Helan there was definitely one there, under the terms of the pre-contract agreement, because he had played for his country.
“Manchester United said it was not possible to negotiate with us but for City now this is dangerous, though we are not expecting a decision from Fifa for perhaps several years.”