The ban on smoking in prisons appears to be ineffective.
New University of Otago research shows almost half of inmates surveyed used cigarettes while incarcerated - and some actually took up the habit while inside.
The research - a pilot scheme which examined whether ex-prisoners remained non-smokers upon release from prison - found tobacco was still present in New Zealand prisons, despite the introduction of a national smoke-free prisons
policy in 2011.
While only a small number of ex-prisoners were questioned, 44% of those who had served their sentence entirely since 2011 said they had smoked while behind bars.
''This pilot study suggests that New Zealand prisons continue to be settings for the uptake or continuation of smoking for many prisoners, including those with a stated desire to be smoke-free,'' the research, published in the latest issue of the New Zealand Medical Journal, said.
However, due to the small size of the survey, further work was needed to corroborate its findings, the authors said.
About 16% of New Zealanders are cigarette smokers, but smoking is vastly more common among prison inmates.
In the most recent prisoner's health survey, 67% of inmates stated they were smokers.
Corrections evaluated the success or otherwise of the smoke-free prisons policy in 2012 and declared it had been a success.
Otago researchers set out to investigate whether prisoners were able to stay smoke-free on release, but also found many were still using smuggled tobacco while inside ''smoke-free'' prisons.
A Corrections spokesman said banning smoking in prisons had resulted in a safer, healthier environment for both staff and prisoners, and resulted in a 72% reduction in fire-related incidents.
''All tobacco and smoking equipment is considered contraband in prison.''
Corrections worked with the Ministry of Health and Quit Group to offer prisoners help to quit smoking - including access to the 0800 Quitline service and free nicotine replacement therapy, the spokesman said.
The Otago researchers found many inmates resumed smoking after release, and called for help to be given to prisoners - both in jail and after release - to keep them not smoking.
''Reintegration staff said their services were focused primarily on preventing recidivism, and therefore helping prisoners stay smoke-free after re-entering the community was not seen as a high priority,'' Sarah Twine, who led the study, said.
''Recently released prisoners told us that staying smoke-free was difficult when returning to social settings where smoking was common.''
Prof Richard Edwards, of the university's public health department, said the research suggested an opportunity was being missed.
''Potentially there is much more that Corrections and community-based reintegration providers could be doing to support prisoners who want to quit,'' he said.
Corrections said it was committed to improving inmates' overall health and wellbeing.
''One of our biggest challenges is ensuring the positive changes made by prisoners participating in rehabilitation and reintegration programmes are sustained when they leave our management.
''This includes connecting them with drug and alcohol treatment providers and Quitline,'' Corrections said.
