POLICE stop and search procedures with no legal basis cost the public purse almost £10 million last year, the Sunday Herald can reveal.

Frisks that failed to find any illicit items in total cost the taxpayer £11.3m, against a backdrop of deep cuts to the police service.

Police Scotland's stop and search policy, aimed at finding drugs, knives and other illegal items, has been under increasing scrutiny since the beginning of the year.

Since April last year, in the first 12 months of the single force, 640,699 searches were carried out.

Research has shown the rate in Scotland is nine times higher than the area covered by the New York Police Department.

Officers carry out two types of search: statutory, the grounds for which are laid down in law, and non-statutory, which have no legal basis and are based on consent of the person who has been stopped. Non-statutory searches have been banned in England and Wales, but are still carried out in Scotland.

The Sunday Herald has now obtained the old Strathclyde Police force's methodology for calculating the cost of stop and searches.

Based on two officers devoting 15 minutes to every procedure, each search in Strathclyde in 2011-12 cost £20.25. Using the same formula, every search carried out by Police Scotland costs £22.

This means carrying out 640,699 searches - the recorded total for 2013-14 - cost nearly £14.1m.

Of this sum, £9.8m was devoted to the controversial non-statutory searches.

In its recent review of stop and search, the Scottish Police Authority, the body which holds the force to account, concluded that the policy used a "significant amount of police officer resource".

The SPA stated in its report: "Based on a Police Scotland estimate of 15 minutes per search including recording, by two police officers, non-­statutory stop and search activity consumes about 250,000 hours of policing effort every year."

Hundreds of civilian police staff have been axed in recent times in order to make deep cuts to the police budget.

The £9.8m figure is estimated to be the equivalent of 400 civilian police staff jobs.

A bigger proportion of the £14.1m - £11.3m - went on searches that found nothing.

According to official figures, fewer than 20% of all searches were successful. This is in spite of Police Scotland insisting that stop and search is an "intelligence-led" policy.

Kath Murray, a doctoral researcher in stop and search at the University of Edinburgh, said: "These figures throw into sharp relief the remarkable allocation of resources to a policy which lacks a credible evidence base.

"The costings also add to existing concerns about the extensive use of non-statutory stop and search, and show how this unregulated and controversial tactic is backed by valuable resources that could be used more constructively elsewhere."

Alison McInnes MSP, the Liberal Democrats' justice spokeswoman, said: "People will rightly question whether spending vast amounts on these high-handed tactics at a time of budget pressures was really the best use of public money.

"For too long the chief constable and the Justice Secretary have defended the way that stop and search was used. But these figures show that the use of stop and search was excessive in every way."

Gerry Crawley, an official with trade union Unison, which represents civilian police staff, said: "The fact that non-­statutory stop and searches have cost £9.8m is deeply concerning considering the loss of 800 support staff jobs over the same period. This money could have saved 400 of those from the axe."

Wayne Mawson, an assistant chief constable at Police Scotland, said: "The public repeatedly tells Police Scotland that tackling violent crime and anti-social behaviour are key priorities for them.

"The use of intelligent stop and search, targeted in the right place at the right time at the right people and for the right reasons, is an essential part of the policing tactics we have at our disposal to help keep our communities safe."