Figures released under the Official Information Act show that of the 8451 prisoners in custody nationwide, 279 were on a sentence of preventive detention as of July 31.
Department of Corrections deputy national commissioner Maria McDonald said the sentence of preventive detention was usually imposed for serious violent or sexual offences.
''This is a lifelong sentence that does not expire or include a specific imprisonment period,'' she said.
The 279 prisoners on a sentence of preventive detention had spent an average 4180 days - or 11 years - in prison.
Twenty-five offenders on a sentence of preventive detention were released on parole between July 1, 2002, and June 30, 2013, with seven released in 2010-11 and six in 2011-12.
Of those released from prison, 14 had been recalled to prison, including three in 2012-13.
''These offenders were subject to very stringent parole conditions and have been recalled to ensure the safety of the community,'' Ms McDonald said.
''The Parole Board has no obligation to release these individuals.''
Corrections Minister Anne Tolley said the Parole Board decided independently whether it was appropriate to release on to parole a prisoner serving preventive detention.
''Prisoners serving a sentence of preventive detention are high risk and only a small number will ever be released.
''The small number of preventive detention prisoners released on parole are closely managed by Corrections for the rest of their lives, and if they breach their conditions, I expect the department to take immediate action and seek to have them recalled to prison.''
Any prisoners serving a sentence of preventive detention must be considered for parole by the New Zealand Parole Board after they have served 10 years of their sentence, unless a longer or shorter minimum non-parole period has been imposed.
Of the 392 prisoners at the Otago Corrections Facility, five were on a sentence of preventive detention on the same date.
Between 1959-60 and 2012-13, five offenders had been sentenced in the Dunedin High Court to preventive detention, with the most recent offender sentenced in 2009-10.
Paedophile teacher James Parker was sentenced in the High Court at Whangarei to preventive detention last month.
