Manchester City sought financial damages from UEFA over their claims of breaking Financial Fair Play laws.
The Sun reports City accused Uefa of “unlawful activities" and demanded damages in their ongoing Financial Fair Play war.
The scale of the fallout over City's FFP case was laid bare in a legal ruling by the Court of Arbitration for Sport.
And legal papers, disclosed for the first time, suggest City chairman Khaldoon Al Mubarak will not accept any Champions League ban.
City allege Europe's governing body LEAKED details over their case and have “systematically breached its express obligations of confidentiality".
Last May, City urged the Lausanne-based court to throw out the FFP case over alleged leaks to news organisations.
The claim was rejected by CAS in November, with Uefa now expected to deliver their verdict in the next few weeks.
But in a signpost to what appears an inevitable appeal if a ban is imposed, City alleged Uefa's probe into their finances has been “contaminated" and “compromised".