Manchester City should face a criminal investigation into an estimated £12 million of unpaid taxes, according to a report.

The report by Tax Policy Associates (TPA) finds Abu Dhabi-owned City could end up facing a bill of up to £24million to settle the amount, once interest and penalties are added.

Its conclusions, centring on the payment of former manager Roberto Mancini, add to the club’s woes after it was found guilty by an independent commission of financial cheating in a major scandal that has rocked the Premier League.

TPA founder Dan Neidle said: ‘We've examined the decision and leaked Mancini documents. We think City likely failed to pay £12 million in tax. There should be a criminal investigation.’

The TPA's report looks at findings by the commission that a key individual – identified via separate leaked documents as then-manager Roberto Mancini – was paid through a ‘sham’ consultancy.

In reality, the contract represented Mr Mancini’s employment by City and the club ‘should therefore have applied UK PAYE income tax in the usual way’, the report said.

But the evidence suggests the club ‘unlawfully failed to do so’, it added.

It was not known whether HM Revenue and Customs (HMRC) has launched an investigation or whether one has been resolved – but there has been no sign of any settlement payments in Manchester City’s accounts, the report said.

TPA continued: ‘The highly irregular nature of the arrangement, and the commission’s findings of sham and intentional concealment, suggest to us that there should be a criminal investigation into whether tax evasion offences were committed.’

The report added that the commission’s findings about City filing false accounts also suggested that ‘criminal offences may have been committed’.

At the heart of the report's claims are payments of £1.75 million a year to Mr Mancini said to cover  coaching services in Abu Dhabi. That was on top of a £1.45 million a season salary to manage Manchester City.

The report said: ‘Mr Mancini was, we assume, fully taxed on his income under his main contract with Manchester City.

‘The club will have applied PAYE to deduct income tax and employee National Insurance from his wages, and paid employer National Insurance on his gross wages.

‘The position for Mr Mancini’s consultancy agreement should have been the same.

‘You can’t magically make a salary untaxed by calling it a consultancy fee. If the payments were really for Mr Mancini’s work at Manchester City, they were employment earnings and should have been taxed accordingly.’

The report adds: ‘We are not suggesting that any specific individuals at Manchester City, or indeed Mr Mancini, committed an offence. We do not know.’

HMRC declined to comment.

Manchester City had yet to respond to a request for comment at the time of publication.