The chief constable of Police Scotland has confirmed he is being investigated for misconduct.
Phil Gormley said he was the subject of a probe by the Police Investigations and Review Commissioner (Pirc).
The investigation followed a referral by the Scottish Police (SPA). Pirc has said that, if the allegations were proved, they would amount to gross misconduct.
Mr Gormley said he was cooperating fully with the Pirc investigation.
There has been no formal indication of the nature of the complaint made against him.
In a statement, Mr Gormley said: "I can confirm that today I was informed by the Pirc that I am the subject of a conduct investigation.
"I am cooperating fully with the Pirc and will provide all necessary assistance to bring this matter to a timely and satisfactory conclusion. In fairness to others who may be involved, it is not appropriate for me to comment further at this time.
"I would like to stress that I remain focused on leading Police Scotland, ensuring that we continue to serve and protect the people of this country."
Analysis by Reevel Alderson, BBC Scotland home affairs correspondent
We understand that the allegations concern Phil Gormley's conduct interacting with a more junior officer.
Normally these investigations would be investigated by the force's professional standards department, but because Mr Gormley is of such a senior rank, the regulations require that it's passed to the Scottish Police Authority.
They don't have any investigation capabilities so they have passed it to the Pirc - and that investigation is now under way.
Mr Gormley has said it is inappropriate to comment further while that is ongoing. In the meantime, he continues to work while he awaits the results of this inquiry.
The Scottish government said it noted the inquiry Pirc investigation but that it would be inappropriate to comment further at the present time.
However, the leader of the Scottish Liberal Democrats, Willie Rennie, said Mr Gormley should consider stepping aside until the matter was resolved.
He told the BBC's Good Morning Scotland programme: "When the senior, the head of the organisation is being investigated, perhaps it would be best if they stood to one side while a quick investigation was under way.
"That's something for him to consider, depending on how serious the allegations are."
Phil Gormley - a career officer
Mr Gormley began his career with Thames Valley Police in 1985.
He was appointed to lead Police Scotland on 2 December 2015.
He served previously as the deputy director general of the National Crime Agency. Before that he was the chief constable of Norfolk Constabulary for three years.
He is a former deputy chief constable of West Midlands Police and also served as a commander in the Metropolitan Police.
Mr Gormley's deputy, Iain Livingstone, announced last week that he plans to retire in the autumn of this year.
Gross misconduct is defined as "a breach of the standards of professional behaviour, as detailed in Schedule 1 of the 2013 Regulations, which is so serious that dismissal may be justified".
These standards cover:
- Honesty and Integrity
- Authority, Respect and Courtesy
- Equality and Diversity
- Use of Force
- Orders and Instructions
- Duties and Responsibilities
- Fitness for Duty
- Discreditable Conduct and Challenging and Reporting Improper Conduct
At the conclusion of a Pirc investigation, it will generally recommend to the SPA whether the allegation should be referred to a misconduct hearing.
An SPA spokesman said: "If an allegation relating to the conduct of a senior officer of ACC rank or above is made, the SPA has the responsibility for receiving and assessing that allegation in line with The Police Service of Scotland (Senior Officers) (Conduct) Regulations 2013.
"If the SPA decides that a misconduct allegation is to be investigated, it must refer the allegation to the independent Police Investigations and Review Commissioner.
"The SPA can confirm an allegation against the chief constable has been referred to Pirc for their investigation. However, consideration of complaints and conduct issues are confidential while being progressed, and the SPA has a policy of not commenting on individual cases."