Scotland's top police officer has raised concerns that an investigation into his alleged misconduct has suffered from "significant delays".
A lawyer representing Chief Constable Phil Gormley insisted the complaints against Scotland's top police officer were "vexatious" and "opportunistic", and said that while Mr Gormley had "maintained a dignified public silence" since the allegations were made, his client had "very serious concerns over the significant delays and proportionality of the investigation being undertaken by the PIRC (police investigations and review commissioner)".
Lawyer David Morgan, who is acting for Mr Gormley, also made clear his client reserved the right to take legal action, stating that a decision to allow him to return to work after he was placed on special leave was reversed.
Justice Secretary Michael Matheson is due to face questions about Mr Gormley's period of special leave, which began in September 2017, at Holyrood on Wednesday.
Ahead of that the Parliament's Public Audit Committee, which has been looking at the work of watchdogs at the Scottish Police Authority (SPA), published letters from the lawyer.
In these, Mr Morgan said that the board of the SPA had made a "unanimous decision" in November that the period of special leave should be rescinded and Mr Gormley should be allowed to return to work.
The lawyer accused Mr Matheson of making an "apparent intervention" to prevent this, saying Mr Gormley had been "surprised" to be told he should not come back after all.
In a letter to the Justice Secretary, Mr Morgan said: "There is no lawful basis for the Scottish Government's intervention or interference with the lawful decision of the SPA, as the sole statutory body tasked with the operational deployment of the chief constable."
In a separate letter to Andrew Flanagan, the then chair of the SPA, Mr Morgan said he was reserving Mr Gormley's "legal rights to challenge any failure to implement the board's decision by way of application for judicial review, should this be necessary".
In a letter to the Public Audit Committee, the lawyer stated: "The complaints against my client are entirely denied. The complaints are vexatious, opportunistic and are being strenuously defended on his behalf."
He added: "Despite the clear and unanimous decision of the SPA board my client's return to work was postponed on the afternoon of November 9 2017.
"My client was travelling back to Scotland in order to resume his duties when he was contacted by the former chair of the SPA Andrew Flanagan, and told not to continue the journey.
"My client was told that this followed a meeting between Andrew Flanagan and the Cabinet Secretary for Justice earlier the same afternoon."
Mr Gormley "remains ready and willing to return to full operational duties", the lawyer said.
A spokesman for the PIRC said: "The PIRC is currently carrying out three separate investigations, which began in July, September and October, into allegations of gross misconduct about the Chief Constable. The Commissioner is committed to carrying out these inquiries in an impartial, independent and thorough manner to get to the truth of all matters.
"This requires that a substantial number of witnesses are interviewed as part of each investigation in order to rigorously pursue and examine all the available evidence, irrespective of whether or not it supports or refutes the allegations made.
"Once that process is complete, the Commissioner will submit her reports on each investigation to the Scottish Police Authority."
A Scottish Government spokeswoman said: "The position of the Chief Constable is a matter for the Scottish Police Authority Board who have kept it under review on a four-weekly basis while an investigation is conducted by the Police Investigations and Review Commissioner.
"As was made clear at last month's Audit Committee, the Scottish Government sought assurances that decisions by the SPA were being made on a fully informed basis including seeking the views of the PIRC."