The law was passed in 2010 by the National government as part of a deal to get support from the Act Party, which had run a "tough on crime" campaign.
It awards "strikes" to those convicted of particular violent or sexual crimes, with second-strike prisoners compelled to serve the full length of their sentences without parole and third-strike offenders to serve the maximum possible penalty without bail.
Data released by Corrections shows 100 inmates serving second-strike offences have now been released, with the group having undertaken 655 courses during their time inside.
Corrections chief custodial officer Neil Beales said plans to return prisoners to society - reintegration - began the first week of an inmate's sentence.
He said prisoners seeking reintegration activities, including release-to-work, which allowed savings to accumulate ahead of release, needed to be eligible for parole in line with Corrections regulations.
"Prisoners with a second or third strike do not have a parole eligibility date, and therefore they do not qualify to take part in temporary release, or reintegration activities that require temporary release outside of prison."
Second and third strike inmates were able to access some reintegration programmes although were restricted from programmes requiring temporary release.
Beales said reintegration services played "an important role in successfully transitioning offenders to the community".
The programmes helped prisoners find accommodation, employment, connect with social services and maintain positive behaviour learned in rehabilitation programmes.
"Reintegration services provide offenders with support to overcome barriers to their successful transition to the community from prison."
Minister of Corrections Kelvin Davis said a second-strike inmate had raised the question with him directly last Friday.
"The feedback they've given me has identified a number of areas I want Corrections to work on, and this particular issue is one of them."
He said change was needed to untangle the legal barrier prohibiting those with second and third strikes from taking part in programmes designed to reduce reoffending.
"We want to look at when reintegration and rehabilitation start. It should start from the day they walk into the prison. We need to look at how to improve things."
Further evidence of second strike and third strike inmates being barred from reintegration programmes emerged in a 2015 Parole Board report for Elijah Akeem Whaanga, who is believed to have been the youngest person sent to prison with a second strike.
Whaanga appeared before the board to receive release conditions in 2015. He was 23 and had completed a 30-month sentence second-strike sentence for aggravated robbery after street muggings which saw people punched and property stolen - a skateboard, hat and cigarette lighter. His first strike followed a conviction for robbery.
The board's report said there was concern over Whaanga's continued links to the Mongrel Mob "given the serious consequences of committing a third-strike offence".
"He believes that he can remain crime-free and continue the connection, but we have our doubts."
The report highlighted safeguards lost because of Whaanga's second-strike sentence.
"Mr Whaanga is frustrated that departmental policies have precluded him from engaging in reintegrative activities while in custody."
The board stated that Whaanga had taken two stages of the national rehabilitation programme and had improved te reo.
It added: "Mr Whaanga needs assistance with his release plan. It is also imperative that programmes and interventions are put in place prior to release so that he is supported immediately following release."
Meanwhile, Justice spokesman Andrew Little has withheld large amounts of political advice received before he attempted to repeal the three-strikes law.
His plan to ask Cabinet to approve scrapping the law was scuppered after opposition from coalition partner NZ First.
Among the scant information release was advice to Little from the Ministry of Justice that there was "no evidence" three strikes had any effect on rates of violent crime.
Little's office said the three strikes material withheld was done so because it related to "political consultation and media discussion".
His office said withholding the information was in line with previous ruling the Office of the Ombudsman had made around "political consultation on Cabinet matters that can outweigh the public interest".
The discovery serious offenders are barred from programmes designed to reduce reoffending comes amid the Government's criminal justice summit, which aims to tackle New Zealand's high rate of imprisonment.
