Manchester City have been found guilty of all charges related to serious breaches of the Premier League’s financial rules over a nine-season period, the league has announced.

The league also said an independent commission had found City guilty of the majority of charges in relation to its failure to cooperate with the league’s investigation.

The league said the commission had found City used schemes “to artificially inflate the club’s revenues, and reduce its costs, by more than £900m during the affected period, to appear to comply with financial rules”.

It said that between seasons 2009-10 and 2017-18 City arranged “sham” contracts (which misrepresented the true agreement between the parties) with a number of their commercial partners, filed misstated accounts and concealed the true state of their finances from its auditors and football regulators.

City say they will appeal “on the basis that the opinion contains clear material errors, of law, principle and fact, and is unsafe”.

The commission found that had information been accurately reported, the club would have been in breach of Premier League and Uefa spending limits “by a very large amount”.

The league said a sanction would be addressed in a further hearing with the independent commission.

Richard Masters, the chief executive of the Premier League, said: “The core decision establishes the facts of what happened at Manchester City during this period. It details how the club systematically broke Premier League rules for nearly a decade.

“It also vindicates the Premier League’s decision to pursue this case against Manchester City. While the process to date has been both long and difficult, the League has remained determined that the facts be established independently.”

City said: “The club is innocent of the accusations made by the Premier League and a comprehensive body of irrefutable evidence exists in support of all of its positions, relating to this case. The club will therefore be relentless, and where necessary proactive, in any and all appropriate regulatory and legal forums.”