SCOTLAND'S pledge to maintain 17,234 police officers has been described as "arbitrary" by the man responsible for holding the service to account.

The move signals the beginning of a national debate about the SNP pledge to create 1000 additional officers in 2007.

Vic Emery, chair of the Scottish Police Authority (SPA), told The Herald that the number of civilian officers is also "to an extent arbitrary" and that both have been shaped by "personal, professional, and political" influences.

He and the other board members at the authority want a wholesale review of the scope, role and scale of policing by leading academics to investigate what is the best number of police officers for Scotland.

The SPA has already begun discussions with academics and different universities to create a group of experts capable of assessing the best ways of policing the country and the numbers of officers required to do so.

The move is likely to prove controversial with opposition politicians who have been keen to hold the SNP to their pledge.

Mr Emery said: "As a country we need to ask ourselves fundamental questions about how Scottish policing will be shaped. We need to ask ourselves what size of police service we need to meet the anticipated demands, and within that what balance of skills and powers we need to achieve a balanced workforce.

"There is a general acceptance that how we have ended up at the figure of 17,234 officers in Scotland has a certain arbitrary element to it. The growth of the civilian workforce through the last decade was also to an extent arbitrary with huge variations across the country in the ratios of police officers to civilians in different areas, sometimes shaped by the personal approaches and interpretations of chief officers and legacy boards.

"So we have inherited a service that has been shaped by multiple influences.

"All political parties have a right to set out the appropriate choices that they would make about a public service as important as policing. What I think the wider political and civic debate would benefit from is some independent input and a more scientific rationale for the scale of police service we need in the future. That would help all parties to better define and shape the future choices and policies that they wish to put to electorates on policing."

Me Emery said there was a role for the SPA in mobilising some fresh thinking on this issue.

He continued: "I plan to encourage a greater involvement for our universities. I have already had initial discussions with a number of senior academics in Scotland, and we will build upon this."

The board also believes Scotland needs weekend courts to bring the country into the 21st century and for prosecutions to be able to keep pace with policing.

A group led by Police Scotland has been created to review the need for Saturday courts.

Lord Carloway, whose review of Scots law underpins the Criminal Justice (Scotland) Bill passing through parliament, raised the prospect of a return to Saturday courts, though the legislation going through Parliament does not make provision for them.

The Lord Justice Clerk said that measures such as Saturday courts should be introduced if, under reforms, suspects still faced being kept in custody without court appearance for more than 36 hours from the point of arrest.

The suggestion attracted opposition from the Sheriffs Association at the time of the Scottish Government's consultation on the Carloway Review amid concerns they would "impose an unacceptable degree of extra strain and excessive extra costs on an already overburdened criminal justice system".

A Scottish Government spokesman said: "We have made clear our commitment to maintaining over 1,000 additional officers in Scotland compared to 2007. The latest statistics show that this Government continues to keep its promise to protect police officer numbers at these levels - in direct contrast to England and Wales where police numbers have fallen to their lowest level in 11 years."