THE Bishop of Worcester has backed a penal reform charity's call for an "open and vigorous" debate on prison privatisation today.

The Rt Rev Peter Selby, who is Bishop to the Prisons, said the policy of encouraging profit-making companies into the sector at a time of rocketing inmate numbers was a question that needed to be addressed.

A new report by the Prison Reform Trust (PRT) - Private Punishment: Who Profits? said the private sector had improved jail regimes in some cases but raised other questions about the wider impact of efficiency savings.

A PRT spokesman said there was a need to "reassess the merits of prison privatisation and the ethics of large companies profiting from the incarceration of thousands of people".

Dr Selby said: "What the Prison Reform Trust is asking is 'are there some specific concerns beyond the general debate about privatisation that apply when prisons are involved'?

"If numbers in prisons need to be reduced - as most agree - is it helpful to create an interest in their growth among companies and their shareholders?

"Are there some real conflicts of interest which we are likely to have to address?

For instance, will judges and jurors have to be vetted to ensure that they do not have an interest in sending more people to prison?"

Even if most prisons remain in public hands, their operation could be "dictated" by privately-run jails, he added.

TUC general secretary Brendan Barber, also backed the report, which raised concerns about private companies' lack of accountability to Parliament and the public's inability to examine contracts signed with the Home Office.

There are currently 10 private prisons in England and Wales. Another private jail is due to open at Peterborough in March.