Scotland Yard has rejected an offer by a police constable caught up in the Andrew Mitchell Plebgate row to resign.
Pc Keith Wallis is facing a potential jail term after he admitted pretending to witness a confrontation between Sutton Coldfield MP Mr Mitchell and officers in Downing Street.
When he entered a guilty plea to misconduct in public office at the Old Bailey earlier this month, it emerged that he had also offered to resign.
But Scotland Yard said: "Pc Keith Wallis has made an application to resign from the Metropolitan Police Service. In line with police regulations the deputy commissioner has the right to refuse the resignation of an officer who has been suspended.
"The deputy commissioner has refused to accept Pc Wallis's resignation and he will face a misconduct board in the coming weeks."
Mr Wallis is due to be sentenced on February 6 and he will then face being sacked.
The 53-year-old from West Drayton, west London, was charged after sending an email to Conservative deputy chief whip John Randall, who was his MP, wrongly claiming he had seen what happened as Mr Mitchell left Downing Street on September 19, 2012.
The then chief whip became involved in a heated confrontation with another police officer, Toby Rowland, after he was refused permission to cycle through the main gate.
The Sutton Coldfield MP later admitted swearing but denied Pc Rowland's claim that he used the word "pleb".
There has been controversy in other cases when officers have retired or resigned and avoided disciplinary proceedings.
Simon Harwood, the constable who caused fatal injuries to newspaper seller Ian Tomlinson during the G20 protests in 2009, medically retired from the Met while facing disciplinary proceedings over an earlier road rage incident.
Mr Harwood was acquitted of Mr Tomlinson's manslaughter in 2012, and in the wake of the case it emerged that hundreds of police officers had been allowed to retire or resign while facing misconduct allegations.
The Daily Mirror found that in the previous four years 791 officers of chief superintendent rank and below had left their jobs while facing claims.
Questions were also raised over the resignation of Sir Norman Bettison, who quit as chief constable of West Yorkshire Police in October 2012 while facing investigation by the Independent Police Complaints Commission.
He was referred to the watchdog after allegations that he gave misleading information in the wake of the Hillsborough disaster.