Police Scotland's chief constable could return to work without prejudicing investigations against him, the head of a policing watchdog has said.

Phil Gormley is the subject of three separate misconduct enquiries and has been on a leave of absence since September.

However, the head of the Police Investigations and Review Commissioner has now said Mr Gormley could resume his duties without prejudicing their work.

In a letter to Jackie Baillie, acting convener of the Scottish Parliament's public audit committee, Kate Frame revealed she was not consulted on the decision to grant Mr Gormley a special leave of absence.

But she noted that she had "real and significant concerns" Mr Gormley might have affected the Pirc's investigation if he had not stepped aside.

Ms Frame wrote: "My concerns mainly arose from the fact that a large number of the witnesses were police staff from the federated ranks and civilian staff who worked within the executive offices at Police Scotland's headquarters and therefore in the immediate vicinity of the chief constable's office.

"Due to the position of power and influence attaching to the chief constable's post, there was a significant concern that those witnesses would not feel free to speak up if the chief constable remained in post."

She concluded by confirming that she told Scottish Police Authority (SPA) head Kenneth Hogg on December 11 that there would now be no problem if Mr Gormley returned to work.

"The chief constable's period of leave in England has enabled my investigation to complete interviews of the more junior members of staff, who perhaps had the greatest fear or repercussions and provided them with a safe space to be interviewed without any immediate fears," she said.

The SPA invited the chief constable to resume his duties in November, according to the Sunday Herald.

The newspaper published extracted of a letter reportedly sent by Mr Gormley's lawyer to the SPA which suggests justice secretary Michael Matheson intervened to prevent his return.

It said he was "concerned that his return was delayed following intervention" by Mr Mathieson.

An SPA spokeswoman said: "The board has agreed that continuing the chief constable's period of leave of absence remains an appropriate measure to address investigative and welfare issues for all parties involved."

The SPA is reviewing the decision every four weeks, with the next review planned on January 25.

Senior deputy chief constable Iain Livingstone assumed responsibility for Police Scotland's day-to-day operations when Mr Gormley stepped aside.

Suspended assistant chief constable Bernard Higgins also faces two separate Pirc enquiries following a tip-off received by the SPA in October.