POLICE Scotland is to go to court in an attempt to block the release of the number of informants it has used in the last four years.

The force will use public money to appeal to the Court of Session against a decision by the country’s transparency watchdog.

Scottish Green MSP John Finnie said: “Police Scotland need to get over themselves on the important issue of scrutiny and not waste public money in support of a court case to save face.”

Paying so-called Covert Human Intelligence Sources (CHIS) has been a part of policing for decades.

The strategy can be used to get vital information on criminals by ensuring police officers have the inside track into their activities.

However, forces on both sides of the border have also been accused of trying to use financial inducements as a way of penetrating peaceful protest groups.

In 2009, it was revealed that the then-Strathclyde Police attempted, and failed, to tap up an environmentalist who was in a group opposed to aviation expansion. The campaigner, Tilly Gifford, taped her conversations with the mystery officers and exposed their approaches.

This newspaper asked Police Scotland how much it had spent on CHIS and how many informants it has had since the force came into being in 2013.

The force confirmed spending around £400,000 in its first two years, but refused the request on the number of CHIS.

An appeal by this newspaper to the Scottish Information Commissioner (SIC) led to the watchdog backing the Sunday Herald.

In its judgment, the SIC revealed the arguments made by the force: “Police Scotland submitted that disclosure of the figure requested would enable Serious Organised Crime Groups (SOCG) to increase their knowledge of the number of CHIS that had operated or were continuing to operate within Scotland.”

The SIC continued: “Police Scotland identified a concern that over time, and if future figures were disclosed, criminals could begin to identify trends and spikes in the number of CHIS and then map these into their own knowledge of individuals within their networks.”

However, in its response, the watchdog rejected the concerns: “The Commissioner considers the submissions she has received are general in nature, speculative, and do not evidence how disclosure of the information requested would be the catalyst of any of the harm claimed by Police Scotland.”

The judgment continued: “Police Scotland also made further submissions that, in the opinion of senior officers, there is a real and significant risk that SOCGs would endanger individuals they suspected (rightly or wrongly) of being CHIS, and their families, if the information requested was disclosed.”

The SIC also dismissed these fears: “The Commissioner fails to see how disclosure of the information requested would place anyone at the remotest risk of identification, or provide any SOCG with the remotest indication that it has been infiltrated, as claimed by Police Scotland.”

The watchdog ordered the force to hand over the information by December 1, but Police Scotland is appealing the decision. Public bodies and applicants can go to the Court of Session if they disagree with a SIC judgement.

In 2012, the SNP Government famously appealed an SIC decision on legal advice relating to an independent Scotland’s position in the European Union, but ministers later abandoned the court bid.

Finnie said: “It seems that Police Scotland have learnt little from the last year’s damning ICCO report and their cynical attempts to circumvent parliamentary scrutiny of their actions.”

Labour MSP Neil Findlay said: "The use of informants is of course a legitimate part of policing, however we have to be sure they operate and are managed within an ethical code. If Police Scotland continues to block legitimate questions being asked about their use then it can only fuel speculation that they have something to hide."

A spokesperson for the SIC said: “I can confirm that the Commissioner has received notification of an appeal by Police Scotland. Given this is a live appeal we can’t comment further at this time.”

A force spokesperson said: "Police Scotland can confirm that an appeal has been lodged with the Court of Session in respect of the Scottish Information Commissioner's recent decision. As court proceedings are now ongoing, it would be inappropriate to offer any further comment at this stage".