Manchester City face “substantial hurdles” if they are to have any chance of winning their appeal after being found guilty of breaking the Premier League’s financial rules, a leading lawyer has told BBC Sport.

City have been found guilty of all charges related to breaches of the Premier League’s financial rules between the 2009-10 and 2017-18 seasons, and creating “sham contracts” to inflate sponsorship deals by £830m.

The club have said they are “innocent of the accusations made by the Premier League” and they have “irrefutable evidence” the ruling “contains clear material errors, of law, principle and fact, and is unsafe”.

In their appeal, City will argue the payments were made by the United Arab Emirates government as a shareholder of the sponsors, while there are inconsistencies in the Commission’s judgement.

Therefore, City say the sponsorship amounts were legitimate and not topped up by the owners.

James Severn, Member of the London Solicitor Litigation Association (LSLA) and Partner at Penningtons Manches Cooper, told BBC Sport the appeal is “not simply an opportunity to invite a new panel” to get the verdict overturned.

“City will need to identify a material error of law, principle or fact, or serious procedural unfairness, which materially affected the Commission’s decision,” Severn said.

“The Appeal Board nevertheless has broad powers to allow or dismiss the appeal, vary the decision or make any other order it considers appropriate.”

Etihad Airways, one of City’s principle sponsors at the centre of the case, had previously stated that the Abu Dhabi government had not paid for its sponsorship of Manchester City.

That came in court documents as part of a US investigation in New York in 2015.

City will argue this does not have the full context of the situation and is not proof they have been inconsistent with evidence.

The club are adamant government documents fully support their case – but, Severin said, if these were already available to the Commission they may not be much use in an appeal.

“The bank statements, government records and contemporaneous payment documents could be powerful evidence if they establish a clear audit trail showing the disputed funds came from the Abu Dhabi government rather than the owners,” Severin added.

“However, if that evidence was already before the Commission, which nevertheless concluded that the arrangements were a sham, City will face an uphill struggle to demonstrate the finding was materially wrong.”

Shortly before City’s appeal was confirmed, Etihad Airways issued a statement saying it had never been “given the opportunity by the Premier League to be represented, to provide relevant information, or to ensure the accuracy and fairness of information relied upon”.

Severin said Etihad Airways’ complaint “does not, of itself, establish procedural unfairness”.

“Etihad was not the respondent and is unlikely to have had an independent right to participate in the proceedings,” Severin said. “It is likely to have been open to either party to obtain and present such evidence to the Commission.

“If the Appeal Board is prepared to consider new evidence from Etihad, it is likely to carry greater weight if supported by contemporaneous documents.”

A key part of City’s defence will be that the Independent Commission relied too heavily on the emails obtained through the Football Leaks files.

“If City can demonstrate the Commission fundamentally misunderstood the emails, failed to consider their proper context or reached conclusions inconsistent with other contemporaneous documents, that could amount to a material factual error,” Severin added.

“City’s difficulty is that the Commission heard extensive witness and documentary evidence but nevertheless made serious findings of sham arrangements and disguised owner funding.”

Kieran Maguire, professor of football finance at the University of Liverpool, told BBC Sport the commission found “the documents were retrofitted to fit the crime”.

“The Commission must have concluded that the evidence and the credibility of the witnesses put up by Manchester City were poor,” Maguire said.

“However, from a legal point of view, this is an area they could attack if Manchester City‘s team can prove that the commission itself was a flawed construct in the sense that the members were Premier League picks rather than Manchester City‘s, and therefore the deck was stacked against the club to begin with.

“But that seems remote.”

Severin added that the retired senior judges and leading barristers, who sat on the Commission, have “spent their careers interpreting complicated facts, dealing with witnesses and applying relevant weight to evidence”.

While adding that it would be “impossible to assess reliably” the chances of City winning their appeal, Severin added that “doing so will not be easy”.

But Maguire believes that while it will be difficult for City to be successful, “there is a route”.

Maguire said: “Given the lawyers that have been recruited by Manchester City, they may go down what’s been described to me as a mess and noise approach.

“That means trying to discredit everything to do with the process of the Commission rather than necessarily the evidence that was presented.

“I’ve seen the documents that Abu Dhabi presented to the New York case. I’m not a lawyer, but from an accounting point of view, they can be seen in more than one way.”

Even though Premier League regulations state an appeal must be heard within 12 weeks, or by Christmas Eve, Severin added that “given the scale and complexity of the proceedings, a final outcome may not be known for some time”.