Scotland's sentencing regime is to be overhauled before the Holyrood elections in May 2007.
By Glenn Campbell
Political correspondent, BBC Scotland
Sources say inmates will not serve shorter sentences
Ministers want to end automatic early release for prisoners given jail terms of less than four years.
A new law is being drawn up based on the work of the Sentencing Commission and details were presented at a meeting of the Scottish Cabinet by Justice Minister Cathy Jamieson.
BBC Scotland understands the executive has accepted plans for a new two-part sentencing system.
The first part of the new sentence would be served in prison, with judges obliged to set a minimum jail term.
The second part of the sentence would involve releasing prisoners into the community under supervision.
Ministers have been warned to expect further demand for prison places which may require another new jail to be built
It's understood offenders would only be considered for this form of early release following a risk assessment.
These changes will be broadly welcomed at Holyrood, but critics will want to know how the system is to be applied.
It's thought judges will be asked to ensure jail terms are not less than half the overall sentence.
In any event, executive sources say there is no question of prisoners serving shorter periods in jail.
Ministers have been warned to expect further demand for prison places which may require another new jail to be built.
A bill to end automatic early release is likely to be published after the Scottish Parliament's summer break.
Ministers are determined to push the new law through parliament before the May 2007 elections.
That will allow ministers, particularly those in the Labour Party, to present themselves as tough on crime in the run-up to polling day.
It is not clear how quickly an end to automatic early release can be implemented.
Given the extra pressures it is likely to place on those who supervise community sentences, there may need to be a transition period to allow services to expand and adapt.