Scotland's prison population is expected to rise by 23% by 2019
The number of prisoners in Scotland's jails could reach almost 10,000 in under a decade, new figures have shown.
Officials are predicting the average daily prison population will rise by 23% by 2019.
Current projections anticipate a record 8,100 prisoners in 2009-10, rising to 9,600 by 2018-19.
The Scottish government report added that the main driver behind the rise was the number of offenders given jail terms of less than four years.
The level of inmates given short sentences has "increased steadily" since 2007, from about 2,600 to 3,500 in 2009, the report said.
Previous figures had shown the average daily prison population in the year to March 2009 was 7,835, up by 6% on the previous year and 31% over the past 10 years.
Justice Secretary Kenny MacAskill said: "These projections confirm what we already suspected - that if current trends continue, Scotland will continue to lock up more and more of its people, many for very short periods.
"This is despite recorded crime being at its lowest level for 30 years."
Mr MacAskill has set out proposals to reduce the number of criminals sent to jail for periods of six months or less, arguing these people should instead be given tougher community punishments.
He added: "Serious criminals deserve to go to jail but they find themselves in prison alongside too many individuals who, quite frankly, would be better dealt with through tough community payback - clearing snow and ice, repairing paths or landscaping parks and gardens."
Mr MacAskill said the Scottish government was investing £120m each year in the prison estate but he said the government was "not prepared" to spend the money building more prisons to accommodate those serving short sentences.
Labour justice spokesman Richard Baker said the figures revealed the inadequacies of the government's approach.
He said: "The SNP's only strategy so far is to see them want to scrap six-month sentences that would see thousands of knife criminals, muggers and housebreakers dodge jail entirely."
Mr Baker continued: "The SNP talk about tough community sentences but they have achieved nothing.
"The fact is that Kenny MacAskill has lost control of the prisons issue and his only strategy is scrapping six-month sentences in a vain and costly attempt to relieve pressure on the system."
Liberal Democrat justice spokesperson Robert Brown MSP called for an overhaul of sentencing in Scotland to stop the prison population "spiralling out of control".
He added: "Rising prisoner numbers is also proof that prison doesn't work as a deterrent.
"Overcrowded prisons mean that serious offenders, who should be in jail, do not get the access to rehabilitation facilities that they need.
"Prisoners are a huge cost to the public purse. Scrapping very short term prison sentences in favour of tough community sentences would save money, reduce re-offending and help cut our prison population."
However, the Conservatives said it would be "dangerous" and against the public interest to argue that fewer criminals should be sent to jail.
John Lamont, the party's spokesman for community safety said: "Prison serves four important functions: to deter criminals, to protect the public, to punish and to rehabilitate. All four matter and we have to have the political will to make prison work.
"In the SNP's soft-touch Scotland, you have to be very unlucky to end up in jail. The prime duty of government is to protect the public. The SNP is guilty of a dereliction of that duty. Scotland is not safe in the SNP's hands."