Back in November, 'Football Leaks' claimed that the reigning Premier League champions has inflated their sponsorship income on their accounts in order to meet UEFA's FFP rules.
City have previously been investigaed for FFP breaches, eventually agreeing to pay a £49m fine back in 2014 in order to settle their case.
However, since the claims made by 'Football Leaks' came to light, UEFA have announced that they will reopen any such case where new information comes to light.
UEFA president Aleksander Ceferin confirmed on Sunday that European football's governing body was keeping a close eye on the situation, saying: "We are assessing the situation.
"We have an independent body working on it. Very soon you will have an answer on what will happen in this concrete case."
In one of the files revealed by 'Football Leaks' City's chief financial officer appears to suggest that a £68m sponsorship deal with Etihad Airlines would actually be paid directly to the club by their owners (the Abu Dhabi United Group).
Despite the claim, City have issued a consistent response to rumours of wrongdoing, saying only: “We will not be providing any comment on out-of-context materials purportedly hacked or stolen from City Football Group and Manchester City personnel and associated people. The attempt to damage the club’s reputation is organised and clear.”
With the integrity of UEFA at stake, the organisation is reportedly ready to act in quick and ruthless fashion should City be found guilty, with a ban from competeing in Europe form as early as next season on the cards.