The number of people locked up in England and Wales could rise by 50 per cent to 92,600 within the next seven years, Home Office officials believe.
A second "middle" prediction, which the Prison Service believes to be the more likely, puts the total at 82,800, up from 63,300. This rise would need 17 more jails to accommodate the extra inmates. Each jail costs about pounds 80m to build.
Richard Tilt, the director general of the Prison Service, expressed his alarm at the possible increase and made a veiled attack on the judiciary for jailing a growing number of offenders. He said: "It's a very expensive programme and people ought to question whether that is the best way to spend public money.
"I think for some of the people who come into the prison they could be dealt with as effectively in the community and at a much lower cost."
Mr Tilt's warning came after the publication of projected long-term trends in the prison population made by Home Office researchers.
The findings are far higher than previous predictions. The Prison Service is currently working on the middle scenario which sees a rise of about 9,000 by 2001 and a further hike to a total of 83,000 in 2005.
Mr Tilt said he had almost secured an agreement with the Home Office to provide more jails in Salford, Pucklechurch, near Bristol, Marchington in Derbyshire, and Onley in Warwickshire. Another 1,200 places would come from new blocks in nine existing jails, about 800 in portable blocks and 2,000 from overcrowding in cells. The Prison Service want an extra pounds 60m for the additional costs.
After 2001 another 12 jails would be needed, or 24 in the worst case scenario, costingpounds 2bn. The new prisons would cost more than pounds 300m a year to run.
The increase in the prison population comes as numbers have risen by 20,000 in four years and places Britain among the world's biggest jailers.
A third "best case" scenario is that the jail population will level off at around 64,400, but with the Prison Service expecting it to reach 65,000 in March, that seems wishful thinking.
The figures will alarm Gordon Brown, the Chancellor, and Treasury officials anxious to keep a lid on public spending.
Today's report says the current increases are because courts are jailing more people for longer. More cases are also coming to court than in the past.
Harry Fletcher, assistant general secretary, of the National Association of Probation Officers warned: "If the Home Office carries on, the costs of punishment are bound to threaten education and other budgets with appalling results."Reuse content