Many prisoners would choose to stay in jail at the end of their sentences because they have nowhere to go when they come out, the governor of Mountjoy prison has said.
Mr John Lonergan described it as a scandal that, for inmates in the more modern prisons, conditions inside were better than what they could expect when freed.
He added that in Mountjoy women's prison, in particular, there were regularly a number of women who could get out but would not leave because there was nowhere for them to go.
Mr Lonergan was speaking at the publication of a report showing that housing is the biggest problem facing six of every 10 people leaving prison.
The report, jointly produced by the homelessness organisation Focus Ireland and PACE, an agency providing services for ex-offenders, also shows that nearly half of a group of ex-prisoners questioned had become homeless while in jail.
The survey is based on interviews with 32 men and 16 women who had been homeless and also spent a term in prison at some point in the last 12 months.
It concludes that the relationship between crime and homelessness is complex, with some respondents reporting that homelessness had led to crime, and others that crime and resulting imprisonment had caused the loss of their homes.
The authors make a number of recommendations aimed at breaking the link between prison release and homelessness.
Chief among these are a call for those sentenced to less than 12 months not to be removed from local authority housing lists, as at present, and an appeal to the judicial system to seek alternatives to custodial sentences for non-indictable crimes, when the offender is at high risk of becoming homeless.
In general, the report calls for more support services to help ex-offenders gain access to accommodation, employment, education and other opportunities.
The chief executive of Focus Ireland, Mr Declan Jones, said this would allow former prisoners to be included in society instead of becoming further marginalised and trapped in a cycle of homelessness that could include crime, substance abuse and other problems, as was happening at the moment.
Mr Lonergan said it was a sad fact that "if you go to court and say I'm homeless, your chance of going to prison is increased". But he sympathised with judges who used prison as a last option for dealing with homeless offenders.
It was also understandable that, for those without a home, prison had its attractions: "People have rights in a prison that they don't have outside, the right to see a doctor immediately, for example," he said.
It cost a minimum of €50,000- €60,000 a year to keep someone in prison, he added, but there was a reluctance to invest in structures that would keep people out of jail.
