POLICE Scotland is embroiled in a civil war after one of the force's most senior officers tabled a series of embarrassing questions about his colleagues.

John Mauger has used Freedom of Information (FOI) legislation to grill the single force about a range of controversial topics, including the qualifications held by his fellow assistant chief constables.

A senior MSP said the move was "unprecedented".

Mauger, 52, served at the Metropolitan and Essex forces before becoming second in command at Central Scotland police in 2009.

However, he was placed on leave in 2010 after facing misconduct allegations of insubordination and inefficiency.

He was off work for three years - a break that cost the taxpayer around £300,000 - before returning in August last year.

Mauger is not listed as one of Police Scotland's six assistant chiefs on the single force's website, but he is deemed a "legacy" ACC.

He does not have an ACC portfolio and is not part of the force's executive. He still receives a six-figure salary, but it is unclear what his current job entails.

The Sunday Herald can reveal that Mauger has taken the extraordinary step of using FOI to extract information on the upper echelons of Police Scotland.

Any citizen can use FOI and Mauger is well within his rights to use the legislation.

He has tabled around 20 requests in this year alone. In February, he asked Police Scotland if each of his fellow ACCs had passed the elite Police National Assessment Centre (PNAC) course required of senior officers.

It later emerged that Ruaraidh Nicolson, the ACC for organised crime, did not have the PNAC qualification. Nicolson had instead graduated from a leadership course run by Ireland's police force that was believed to be a "relevant" qualification.

Mauger also asked the Scottish Police Authority (SPA) whether any of the six ACCs had declared outstanding complaints during the application process for the posts.

He also quizzed Her Majesty's Inspectorate of Constabulary in Scotland on confidentiality agreements and asked about the vetting clearance of SPA board members.

Many of his initial questions, tabled last year, related to his own personal case.

It is understood Mauger was originally put on leave in 2010 after he raised questions about how public money was being spent in Central Scotland police.

A police source said of Mauger's original motive for going down the FOI route: "John started asking questions publicly to show the total abuse of process, regulations and legislation and the dishonest, irrational and totally malicious use of the misconduct process."

The source added: "He wanted to show the many failures and the sheer cost of all of this."

Graeme Pearson, Scottish Labour's shadow justice secretary, said: "It is unprecedented to have a member of the police service 'FOIing' his own service. It also very strange that, having been on gardening leave for so long - a term unknown in police discipline - Mr Mauger returns to work but no formal process is on record and no explanation given as to why he was not working but being paid a substantial salary for over two years.

"Something smells rotten here and no-one seems to want to be associated with it. As usual, the public have paid the cost of the incompetent handling of the situation which runs into hundreds of thousands of pounds and Kenny MacAskill has consistently ignored it."

Scottish Liberal Democrat justice spokesperson Alison McInnes said: "Every person has a right to use Freedom of Information laws but these requests might raise eyebrows about the state of relationships at the very top of Police Scotland."

A Police Scotland spokesperson declined to comment on the FOIs, but said: "Assistant Chief Constable John Mauger is involved in project work within the Operational Support Division at Police Scotland under the direction of Deputy Chief Constable Iain Livingstone."

Mauger, all allegations of misconduct against whom were withdrawn on Friday, could not be reached by the Sunday Herald.