PLANS to end the automatic early release of long-term prisoners need further examination before proposed changes are brought into force, a key committee of MSPs has warned.

Members of Holyrood's Justice Committee, with the exception of rebel Tory MSP Margaret Mitchell, backed the general principle of the Scottish Government plan, which would see criminals sentenced to four years or more no longer released automatically two-thirds of the way into their sentence before serving the remainder on licence in the community.

However, a report on the Prisoners (Control of Release) (Scotland) Bill calls on ministers to answer more questions about the cost of their proposals, while stating it is vital that offenders are still subjected to a meaningful period of supervision in the community to help them reenter society.

Justice Secretary Michael Matheson has said that he is willing to make concessions after academics raised a series of concerns, including that releasing prisoners 'cold' at the end of their sentence with no support or power to recall them to jail would increase risk to the public, rather than reduce it.

Mr Matheson has said an automatic period of supervision will be added in response to concerns, but the committee has called for further clarity over how the change would work in practice, saying a letter sent to them provided insufficient details.

Critics have pointed out that including a period of supervision during a sentence is what happens currently, while adding requirements on offenders after a jail term has expired may breach human rights laws.

The committee also raised concern about the availability of rehabilitation programmes in prison, and called on the Scottish Government to publish updated estimates on how much its proposed changes would cost.

The report states: "The committee has concerns that demand for certain programmes may currently outweigh supply and recommends that an independent assessment be carried out."

The new law would see long-term prisoners potentially spend years longer in jail, while demand for courses would be likely to increase as offenders would have to prove themselves worthy of early release to the parole board.

Fergus McNeill, Professor of Criminology and Social Work at the University of Glasgow, said he broadly supported the committee's recommendations.

"I think the lack of clarity on the detail of what is now being proposed by the Government makes it difficult to reach a judgement on the merits of the Bill as it stands, which forces to committee to simply endorse the Bill's broad objectives," he said.

"Basically, it means that a lot of work needs to be done at stage two. I hope that sufficient time will be allowed to ensure that evidence can properly inform the process at that stage."