Former Manchester City chairman David Bernstein said the club could face potentially "drastic" sanctions after reportedly being found guilty on all but one of 115 charges for breaching Premier League financial rules.
No official announcement has been made by the Premier League over the case, and there is no indication of any possible punishment.
Abu Dhabi-backed City have always strenuously denied the charges and a club spokesperson said the position had not changed.
It is understood City will appeal should the charges be upheld.
"The club has diligently respected due process for eight years on the basis that the Premier League board and executive would behave as an independent, impartial and fair-minded regulator, free from partisan influence," the spokesperson said.
City were charged by the Premier League in 2023 following an investigation into alleged breaches of rules between 2009 and 2018.
The club were accused of failing to provide accurate financial information and details of payments to players and coaches, as well as breaches of financial sustainability rules.
They were also charged with failing to cooperate with an investigation.
A hearing by an independent commission started in September 2024.
'SEVERE PENALTY'
Bernstein, who was City chairman between 1998 and 2003, told Times Radio that "money is not sufficient" in terms of a potential punishment, urging a swift appeal process.
"The appeal process cannot go on for year after year, I think that would be a disaster," he said. "Not just for this particular case but for English football generally. The timing is crucial.
"I can't give a view on the punishment. If they are found, after the appeal, guilty of (the) charges, my beloved club is going to face a very severe penalty.
"All I would say is that money is not sufficient, it would have to be something, unfortunately, more drastic than that."
Oasis star and City fan Noel Gallagher described his "shock" at the developments.
Speaking on the Let Me Talk podcast, he said: "Surprised because only that the club have assured us all along that they vehemently denied any of these charges.
"So it was a bit of a shock to find out that we've been found guilty of all but one. But really overall just quite sad really. Sad for the fans and for the players."
UK culture secretary Lisa Nandy described the case as "unsettling" for football fans and called for a swift resolution.
In 2020, UEFA imposed a two-year European ban on City as well as a fine for breaking financial fair-play rules, though that ban was later overturned by the Court of Arbitration for Sport.
If the reported guilty verdicts are confirmed, sanctions could include a severe points deduction and possibly even expulsion from the Premier League.
Everton and Nottingham Forest were both hit by points deductions in the 2023/24 season for single breaches of profit and sustainability rules.
Other Premier League clubs are understood to be taking legal advice about compensation relating to the charges.
Under the ownership of Sheikh Mansour, whose Abu Dhabi United Group acquired the club in 2008, City have become the dominant force in English football.
They have won eight Premier League titles, a Champions League crown and multiple other trophies over the past 15 years.
The latest developments in the case come just months after former City manager Pep Guardiola left the club following a golden decade in charge at the Etihad.
Guardiola always backed the club's stance on the charges but threatened to walk away if he felt he had been lied to and they were proven to be true.