UEFA has launched an investigation into Manchester City over a potential breach of Financial Fair Play rules.
The Investigatory Chamber of the independent UEFA Club Financial Control Body made the announcement in response after allegations made in German publication Der Spiegel. Claims purportedly obtained by whistleblowers Football Leaks, claim the English champions circumvented FFP rules by inflating sponsorship deals.
The European football governing body said in a statement: "The Investigatory Chamber of the independent UEFA Club Financial Control Body has today opened a formal investigation into Manchester City FC for potential breaches of Financial Fair Play (FFP) regulations.
"The investigation will focus on several alleged violations of FFP that were recently made public in various media outlets.
"UEFA will make no further comments on the matter while the investigation is ongoing."
A statement from the club said: "Manchester City welcomes the opening of a formal UEFA investigation as an opportunity to bring to an end the speculation resulting from the illegal hacking and out of context publication of City emails. The accusation of financial irregularities are entirely false. The Club's published accounts are full and complete and a matter of legal and regulatory record."
City have already been punished for violating FFP, striking an agreement in 2014 that saw them fined rather than banned from the Champions League for inflated sponsorship deals with companies linked to the club or their ownership. UEFA said last month that evidence from Football Leaks could lead to past cases being re-opened.
If found guilty, it has been claimed that City could face a potential ban from the Champions League.