Harvey's letter is alleged to have outlined the argument which Leeds planned to present to the arbitration hearing, which started on April 16 and heard final submissions from both Leeds and the Football League last Monday.
A report claims the letter may have breached FA Rule K6, which insists on confidentiality surrounding arbitration cases.
However, the basis of United's argument was already in the public domain before Harvey's letter was sent, having been submitted to the High Court in February.
Leeds served a writ on the Football League on February 5, and their grievance is detailed in a 27-page claim form issued in the High Court of Justice on February 12.
Harvey said in the YEP: "It wouldn't be appropriate for me to make any comment at this time."