Scotland should abolish automatic life sentences for murderers, according to a leading international justice expert.

Professor Dirk Van Zyl Smit said the country - which has twice as many 'lifers' as France - had a get-tough penal system which was increasingly out of kilter with the rest of Europe.

The South African insists “not all murderers are equally dangerous” and urged Scotland to follow the example of places like Norway — where far right terrorist Anders Breivik was given a maximum sentence of 21 years for killing 77 people.

READ MORE: David Leask on the meaning of life for murderers

Scotland, Prof Van Zyl Smit said, is now proportionately sentencing more people to life than any other European country, including England and Wales.

In absolute terms, Scotland has around 1,000 life prisoners and England about 5,500. By comparison, Russia has 1,800 prisoners serving life whereas France has 500.

Countries like Russia and France only sentence the most serious killers to life, such as terrorists or child sex murderers. Germany gives life to all murderers but has a very narrow definition of the crime of murder.

Other nations such as Uruguay and Norway have abolished lift sentences altogether but can keep someone locked up on public safety grounds.

The Scottish Government in recent years has been accused of adopting "soft-touch" justice policies by right-wing opponents and commentators.

However, figures show it has one of the highest incarceration rates in western Europe.

Professor Van Zyl Smit said: "Scottish people often have an idea of the criminal justice system as not being as harsh as elsewhere. At the top end that is not true.

"The UK has the highest rate of life sentencing in Europe and Scotland sentences more prisoners to life, proportionately, than England," he said.

"The UK and Turkey together have more lifers than the rest of Europe put together, including Russia.

"There is a hard question about what you do with your worst offenders.

"The main concern is that numbers are burgeoning here, while some countries do not have life sentences at all."

Herald View: Verdict on criminal justice - serious reform is needed

One of the reasons life sentences are controversial in Scotland and the UK is because they do not usually mean a prisoner remains in prison for the rest of their life.

Scottish judges must sentence for life but they also add a minimum tariff that a convicted killer must serve. Analysis shows these tariffs have been creeping up with Prof Van Zyl Smit suggesting a growing number of lifers behind bars was "storing up" problems for the future. The longest so far was 37 years. All released lifers, however, are out on licence for the rest of their life regardless of the length of their sentence.

Barlinnie, Glasgow's Victorian prison

The Herald:

Some right-wingers, including the Scottish Conservatives, have called for life to mean life whole life sentences. Prof Professor Van Zyl Smit said such policies were "arguably illegal" in terms of European human rights law.

He added: "More than 30 countries have neither the death sentences nor life sentences," he said. "Others use them more sparingly."

"People who defend the system say we reflect the seriousness of the offence in a life sentence and the minimum period lifers have to serve before they are eligible for release."

BACKGROUND: Detailed look at Scotland's pensioner prisoners

Professor Van Zyl Smit said the reasons for Scotland's high rate of life imprisonment were complex and multiple.

His said: "You need to look at mandatory life sentences for murder – not all murderers are equally dangerous – and at what sort of minimum period is being set. After that minimum period are you releasing people? And more and more people are being recalled to prison.”

The professor, who is at the law department of Nottingham University, was speaking ahead of a speech to the Howard League for Penal Reform in Scotland.

His words were welcomed by the charity, which said: "This lecture questions whether life sentences from which offenders may never be released are human rights compliant. It also asks what can be done to reduce the number of persons serving life imprisonment by considering what the alternatives could be to life-long imprisonment.”

A spokesman for Scottish Conservatives said: "This analysis doesn't consider victims of crime, a group who are sick and tired of being overlooked by government and experts."

READ MORE: David Leask on the meaning of life for murderers

A Scottish Government spokeswoman did not address the proposals for legislative reform. But she said: “Sentencing decisions in each individual case are determined by the courts."

The Herald:

Former Scottish Justice Secretary Kenny MacAskill (pictured above) said there was no "no quick fix" to the issue. He added: "We have become a more retributive society and with some heinous crime there’s been an understandable clamour for increased sentences. It seems to me that the Sentencing Commission should be asked to consider the situation as to disparities with elsewhere.

"However, it's likely to have to be a wider consideration by us as a society as to how we see not just punishment but rehabilitation."