ONE of Scotland's top lawyers has launched a scathing attack on proposals to end automatic early release of long-term prisoners, accusing the SNP of adopting a "bogus, populist position" that will do nothing to improve public safety.

Brian McConnachie QC, an ex-chairman of the Faculty of Advocates Criminal Bar Association and former Principal Advocate Depute at the Crown Office, said the Scottish ministers had engaged in "pure electioneering" over the flagship policy, playing to public misconceptions about the justice system.

First Minister Nicola Sturgeon has said she wants to stop prisoners sentenced to four years or more being automatically released two-thirds of the way into their sentence and serving the remainder in the community on licence, a move that would potentially lead to hundreds of criminals spending longer behind bars. Instead, prisoners would only be released early with parole board approval.

A Bill currently making its way through Holyrood has been criticised by a series of experts, who have said there is little evidence that jailing people for longer prevents them committing further offences on release. Concern has also been raised that periods of supervision in the community, which currently sees offenders returned to prison if they misbehave, will be insufficient to effectively re-integrate them into society harming chances of rehabilitation.

Mr McConnachie said: "If you force someone to serve all of an eight year sentence, then you say 'that's eight years up, cheerio,' then what do they do next and what control do you have over them?

"What are they trying to achieve here? Truth be told, it's not protection of the public that's really the issue. This is an effort to go to the public and say 'we stopped this, we have kept people in custody '. But it's a bogus, short-term, populist measure so they can claim to be the party of law and order. It's a shallow attempt at that, pure electioneering."

Justice Secretary Michael Matheson has suggested a compulsory three to six months of community supervision would be served at the end of sentences in response to concern over the dangers of 'cold release', but Mr McConnachie warned the period was insufficient.

He added: "Let's say they don't cooperate, is that going to be a criminal offence? Returning them to jail for just a few months isn't much of a sanction. The system, as it currently stands, works as well as any. Of course, people will be released and still commit crime, but it's pretty rare for someone on release from a long-term sentence to commit offences of a similar type. It tends to be that they get involved in something daft, and going back to serve the rest of a sentence is as significant punishment.

"Like a great many things this Government has done, very little thought has gone in to it. They go through the motions of asking so-called experts, then they ignore them.

"Prison is not just about punishment, that's part of it but it's ultimately about trying to rehabilitate someone. Putting folk in jail for longer is not the way forward for rehabilitation."

Experts have said the current proposals would amount to the most radical change to release arrangements for two decades. The current system was established in 1993 following the recommendations of a committee led by Lord Kincraig, an ex-Senator of the College of Justice in Scotland, which was established in 1987 and published its report two years later.

Critics have pointed to a lack of evidence behind the Scottish Government proposals, which have attracted support from victims' organisations. Mr Matheson this week insisted that his plan would protect the public, saying that offenders released following parole board approval were seven times less likely to reoffend than those released automatically.

However, Mr McConnachie said the comparison was "totally misleading", accusing the minister of "comparing apples and pears". He also raised concern about the large cost of keeping offenders behind bars for years longer, saying the cash could be better spent elsewhere.

A Scottish Government spokesman said: "The focus of this Bill is to improve public safety. Our legislation means the independent Parole Board will have the powers to determine whether a long-term prisoner should be authorised for release and the appropriate period of supervision in the community, rather than prisoners having to be released automatically at the two-thirds point of their sentence."