The automatic early release of many criminals is to end under new measures being drawn up by Scottish ministers.
A new two-part sentencing system is under consideration
A two-part sentencing system will be introduced, with an end to the unconditional release of inmates serving jail terms under four years.
The first part will consist of a minimum jail term and the second will be served under licence and supervision in the community.
Ministers want to legislate before the Holyrood elections in 2007.
They have broadly accepted a system proposed by the Sentencing Commission.
The Scottish Executive set up the commission in November 2003 after identifying the issue of early release as a policy priority.
The commission reported back in January of this year with a number of recommendations,
These included a provision that inmates serving more than 12 months should serve a fixed minimum period in jail followed by a further part of their sentence in the community, provided they do not pose a risk to the public.
BBC Scotland political correspondent Glenn Campbell said: "Executive sources said the system proposed by ministers would not mean criminals serving shorter spells in prison.
"If anything, it is thought the reforms will add to Scotland's growing prison population."
Glenn said ministers have been warned that demand could force the need for a new prison to be constructed.
Scottish Conservative leader Annabel Goldie reacted with scepticism to the development and said Labour, their Liberal Democrat coalition partners and the SNP had consistently refused to back an end to early release in the past.
She said: "If this is the beginning of the executive ditching their rhetoric and actually getting tough then it is very welcome.
"However, recent history - such as the Management of Offenders (Scotland) Bill - shows us that Labour and the Liberal Democrats are more interested in letting people out of jail even earlier than they are in protecting the public, making punishments fit the crime and introducing honesty in sentencing."