German news magazine Der Spiegel says City and PSG overvalued sponsorship deals to help meet Uefa's Financial Fair Play (FFP) rules.
Now, the second of four promised exposés from the publication focuses on other ways City attempted to come up with "creative solutions", leading to the launch of "Project Longbow".
Under UEFA's "Financial Fair Play" rules, clubs must be transparent about revenues and broadly balance them against expenditure. It led to apparent threats of legal action from the club and indignation to the point where City fans still gleefully greet the UEFA anthem with a chorus of boos on Champions League nights.
CIty have said they will not comment on the claims. "Incredible people working here, and how professional they are in all the departments", he said.
City have already been fined £49m in 2014 - £32m of which was suspended - for a breach of FFP rules.
"We will need to fight this", Soriano wrote, according to the magazine, "and do it in a way that is not visible, or we will be pointed out as the global enemies of football".
Der Spiegel claims that part of it saw many operational costs to be "shifted either fully or partially" away from City. Usually clubs pay players for their image rights.More news: AP Source Suns buying out Tyson Chandler
The scheme is said to have involved a shell company called Fordham Sports Management being set up.
City CEO Ferran Soriano complained in one memo that ECA members were pushing for the UEFA rules - which many thought could curb the rise of Man City and Qatari-owned Paris Saint-Germain.
The external company paid City "almost 30m euros" (£26m) and were then reimbursed approximately £11m a year in secret by owner Sheikh Mansour's holding company, Abu Dhabi United Group. Taking that further, it is declared that 'Fordham was merely a vehicle for hidden capital injections from Abu Dhabi'.
"I am inside now for the past three years and I would say of course like many, many clubs around the world there is a lot of money, but they are an incredible club". At the time of the email, France legend Michel Platini was Uefa president.
"You have to accept it when people say you win just because of money, what can you say?"
When asked about the accusations, the manager Pep Guardiola insisted that City had always tried to do things the right way.
In August Man City celebrated the 10th anniversary since Sheikh Mansour, a member of Abu Dhabi's ruling family, took control of the club, pouring billions into player budgets and infrastructure to turn the perennial Premier League strugglers into champions.