UEFA has opened a formal investigation into whether Manchester City has violated financial monitoring rules, after confidential club documents were published in the Football Leaks series.
In the most serious cases of breaking "Financial Fair Play" rules designed to control excessive spending on player transfers and wages, UEFA can ban clubs from the Champions League.
UEFA said Thursday its independent club finance panel is focusing on "several alleged violations of FFP that were recently made public in various media outlets."
Internal documents about Man City's business and emails between club executives have been published in the Football Leaks series led by Der Spiegel magazine.
The revelations suggest Man City officials deceived UEFA over several years, including by disguising the source of revenue from sponsorship deals tied to the club's owners in Abu Dhabi.
In one batch of communications between Man City officials, the club seemed ready to threaten to destroy UEFA with legal action before reaching a 2014 settlement agreement to close an investigation.
Then, Man City forfeited 20 million euros ($22.8 million) in Champions League prize money but continued to play in world soccer's most prestigious club competition.
Man City has repeatedly declined to address specific allegations, and have not contested the authenticity of the documents.
"The attempt to damage the club's reputation is organized and clear," the club has said since November.
The Pep Guardiola-coached team is currently top of England's Premier League, seeking its fourth league title in the past eight seasons. The team hosts Schalke next week in the Champions League, holding a 3-2 lead from the first leg.
Since July 2011, UEFA has monitored the accounts of all clubs which qualify to play in the Champions League and Europa League.
Launched as the flagship policy of UEFA's then-president Michel Platini, it was designed to force clubs to break even on their soccer-related income and spending to prevent clubs from becoming unsustainable. It also sought to control wealthy owners distorting the market in transfers and wages by driving up costs.
Critics of FFP say it protects historically successful clubs with global brands from being challenged by ambitious newcomers.
The biggest forfeits were paid in 2014 by Man City and Paris Saint-Germain, which were bought using sovereign wealth respectively by Abu Dhabi's ruling family in 2008 and Qatar's in 2011.
UEFA gave no timetable for the case, stating it "will make no further comments on the matter while the investigation is ongoing."
