Three officers have already been dismissed over the infamous altercation at the gates of Downing Street, but two misconduct hearings have yet to reach their conclusion.
A Metropolitan Police spokesman said such hearings are legally private and that it does not want to jeopardise the two outstanding cases, one of which is part heard.
A Met spokesman said a report detailing the investigation into the row will be published “in due course”. He added: “We can confirm we have received a letter from Mr Mitchell today, Tuesday May 20.
“We have already sought legal advice as to what information it is possible to publish after the conclusion of the gross misconduct hearings.
“Statutory regulations govern police misconduct proceedings and state they are considered a private process.
“As such the information raised at misconduct hearings is treated as confidential. However, the MPS has already stated publicly that a report detailing the Operation Alice investigation will be published in due course.
“We also intend to publish the summary reports from the chair of the gross misconduct boards.
“Mr Mitchell is aware that we will inform him in advance of publication what will be released, and when.”