The Scottish Chief Police Officers Staff Association, which is made up of Scotland’s most senior officers including chief and assistant chief constable ranks, has written to the Government to say the decision not to advertise the job of Her ­Majesty’s Inspector of Constabulary breached equality and employment legislation.

A source said: “Chief constables raised the issue with civil servants on a number of occasions and then the staff association wrote to them officially to raise concerns that they were in breach of equality legislation.

“We understand that the post will be advertised in the new year.”

Established more than 150 years ago, the £180,000-a-year inspectorate role had been prominent in providing independent advice to ministers and holding Scotland’s eight forces and other police bodies to account.

However, when Paddy Tomkins retired as chief inspector in April, ministers said the post was “under review” and later admitted that Bill Skelly, the acting inspector of constabulary, would take over permanently without the full salary.

Mr Skelly, an assistant chief constable seconded from Lothian and Borders, was appointed as head of the inspectorate under royal warrant but

is not the “chief inspector” and receives a salary £30,000 lower.

Traditionally, the chief inspector has held chief constable rank, but on June 24 Mr MacAskill created a Scottish Policing Board and said the inspectorate would continue under Mr Skelly.

The move followed heightened tensions between chief constables and the Government in relation to how many forces there should be in future and how issues such as counter-­terrorism should be handled.

In July, The Herald revealed that senior police chiefs had accused civil servants and ministers of deliberately attempting to undermine the independence of policing through changes to the inspectorate.

The Association of Chief Police Officers in Scotland (Acpos) and police boards, including Strathclyde Police Authority, wrote

to Justice Secretary Kenny MacAskill warning that the current arrangements risked undermining the credibility and independence of the post and placed him at “substantial risk”.

Colin McKerracher, one of Scotland’s most senior chief constables, said at the time: “The Government has fudged the issue by saying the current arrangement will continue.

“We need someone who can stand up to chief constables, look them in the eye and say they don’t think they are doing things properly. Bill Skelly was a junior Acpos officer before being seconded to the inspectorate and I don’t think he has the experience to challenge chief constables. It is unfair to ask someone with his experience to take on that role.”

A Scottish Government spokesman said: “This position has not yet been advertised. The Scottish Government greatly values the role played by HM Inspectorate of Constabulary for Scotland and the independent advice it provides all policing partners.

“Under current temporary arrangements, the inspectorate continues to fill this role effectively under the leadership of Her Majesty’s Inspector of Constabulary, Bill Skelly.

“The process for filling this post on a permanent basis will begin in the New Year. Before advertising this position, we are consulting police conveners and chief constables about the job specification required for this role.”