Ulster's prison population is predicted to rise by almost 25% over the next five years, the Belfast Telegraph can reveal.
It is estimated that by 2013 there will be an average of 1,835 inmates each year behind bars in Ulster - 355 more than the average number expected for the end of this financial year.
The Government has predicted there will be a 5% increase in prisoner numbers from 2007/08 to 2008/09 and a 4% rise in each following year up to 20012/13.
The predicted rises are understood to take into account those offenders who, from spring 2008, will receive an indefinite term behind bars as part of the new public protection laws.
In a bid to avert the overcrowding crisis in England and Wales the Government is planning to introduce at least 180 new jail places by the end of the 2008/09 financial year to meet the increased number of remand and sentenced prisoners.
This will increase the number of prison places in Northern Ireland to 1,775. Currently there are 1,470 inmates housed across the prison estate - Maghaberry, Magilligan and Hydebank.
Policing and Justice Minister Paul Goggins is expected to reveal plans before the end of the year to develop the prison estate in a bid to accommodate more adult male prisoners.
In response to a parliamentary question about prison population submitted by South Down MP Eddie McGrady, Mr Goggins said: "The service currently has 1,595 cells and plans to add a minimum of 180 additional places by the end of 2008/09.
"On February 21 this year, I asked the Prison Service to carry out an options appraisal on the development of the estate for holding adult male prisoners.
"I intend to make an announcement before the end of the year on the service's plans to meet the accommodation needs of the updated projected population."
From May next year, for the first time in Northern Ireland, the authorities will be able to keep non-life prisoners behind bars indefinitely if they pose a risk to the public.
However, those in receipt of a Public Protection Sentence are not expected to greatly increase prison population as the Government is planning to deal with less dangerous offenders in the community.
Details of how much the development of the prison estate is likely to cost have not yet been revealed.
However, based on the current average cost of keeping an inmate, it is estimated that within five years almost half-a-million pounds could be forked out each day on the prison population.
Earlier this year the Chief Inspector of Prisons, Kit Chivers, revealed that last year each inmate cost an average of £236.41 a day to keep.
This is more than a stay in one of the province's top hotels.
A deluxe double room at the luxurious Merchant Hotel in Belfast costs £220 a night. An executive single room with garden view at the exclusive Culloden Estate in Cultra costs £200.