POLICE Scotland is trying block the release of the number informants it has had over fears disclosure will have a “chilling effect” on other individuals coming forward.

In a court appeal against a decision by the Scottish Information Commissioner (SIC) the force has also argued that disclosing the figure would set a “precedent” and may lead to more requests being made.

However, Scottish Greens MSP John Finnie described the arguments as “lame”.

Police have for years used informants – formally known as Covert Human Intelligence Sources (CHIS) – as a tool to gain valuable insights into criminal activity. The practice has attracted scrutiny, however, over claims police forces have tried to pay informants to spy on peaceful protest groups.

As a way of shedding light on the general policy the Sunday Herald asked Police Scotland for a copy of its standard operating procedure on CHIS, how much the force had spent in this area since 2013 and how many CHIS had been recruited in the same period.

The force answered the first two questions, but refused to say how many informants have been on its books.

No geographical breakdown was requested and the total number of CHIS is already published on a UK-wide basis.

The SIC, which adjudicates on information disputes, backed this newspaper and ordered disclosure.

The force argued the information could help serious and organised crime groups (SOCG), but the SIC concluded: “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.”

Police Scotland is now using public money to challenge the SIC decision at the Court of Session and an appeal was lodged earlier this month.

The appeal, which is in the name of chief constable Phil Gormley, lays out three grounds.

The first argument states: “The Commissioner does not address, directly, or indirectly, the chilling effect or, more generally, the effect that disclosure of the disputed information might have on individuals who were or might become CHIS.”

Police Scotland also warned of a “precedent effect” that might lead to similar requests being made in the future:

“For instance, if Mr Hutcheon or another party renewed the request six months after his original request, it would become clear whether or not the Appellant [Police Scotland] had recruited additional CHIS during a particular six-month period. A marked increase in numbers would indicate that the Appellant had been active in recruiting CHIS.”

In its final submission the force argued that the Commissioner had “erred” by disregarding warnings by senior officers on effects of disclosure.

“Where specialists in a highly-sensitive aspect of crime prevention had identified the potential effects of disclosure and having regard to the potential consequences for the CHIS themselves, the Commissioner acted unreasonably in failing to place more weight on the submissions that she had received from the Appellant.”

Finnie said: “The excuses for being unwilling to accept the Scottish Information Commissioner’s ruling on this matter are lame. It would seem that I have more confidence in Police Scotland’s ability to continue to secure legitimate information sources than they do.

“The police appear to have learnt nothing about how to handle legitimate press enquiries about an area which it is acknowledged has sensitivities but none than can over-ride legitimate public interest."

Labour MSP Neil Findlay said: "I find it extraordinary the lengths Police Scotland will go to try to avoid accountability. The public have to have confidence in the force and frontline officers across the board do great work, but they are being let down by really bad decisions being made by senior officers."

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".

A SIC spokesperson said: “I can confirm that the Commissioner will be defending the appeal. Given this is a live appeal I’m afraid that we can’t comment further.”