Phil Gormley, on leave since July, says it would be impossible for him to resume his duties

The head of Police Scotland has resigned with immediate effect, saying it was impossible for him to resume his duties in a meaningful way.

Phil Gormley, who was named chief constable of the UK’s second-largest police force in December 2015, has been on special leave since July pending an investigation into a string of misconduct allegations against him. He denies any wrongdoing.

In a statement, Gormley said: “The past eight months have been difficult for me and my family. In particular, I would like to thank my wife for her love and loyalty.

“The events since November 2017 have led me to the conclusion that it is impossible for me to resume my duties in a meaningful way prior to the end of my contract. I now need to prioritise the health and wellbeing of my family, on whom these events have taken a significant toll.”

The Police Investigations and Review Commissioner is investigating four complaints of bullying, while three are being assessed internally. The latest complaint, which was lodged at the end of January, is understood to have been made to the Scottish Police Authority by the Scottish Police Federation, which represents rank-and-file officers.

Susan Deacon, the chair of the SPA, thanked Gormley for his contribution to Scottish policing. “This has been a challenging period for all concerned, and in the interest of policing in Scotland, we now need to move on,” she said.

His resignation marks the latest stage in a tumultuous period for the force. Four other senior officers have been suspended in recent months, two as part of a criminal inquiry into the unauthorised use of a police firing range.

The saga took on a significant political dimension when Gormley’s lawyer accused the Scottish justice secretary, Michael Matheson, of acting unlawfully by intervening in a decision by the SPA to allow the chief constable to return to work in November.

Subsequent revelations that Matheson had told the SPA it was “a bad decision” brought calls for the justice secretary to consider his position, which were reiterated on Wednesday following Gormley’s resignation.

The shadow Scottish justice secretary, Liam Kerr, said: “Mr Gormley makes clear in his resignation statement that it was the events of November 2017, when Michael Matheson intervened to prevent his return to work, that made it impossible for him to carry on.

“It suggests that, less than two years after his appointment, the SNP government intervened to force him out. Michael Matheson may hope that the stink hanging over this affair will clear with Mr Gormley’s departure. It won’t. That will only happen when Mr Matheson does the decent thing and follows the former chief constable out of the door.”