An extra 2300 prisoners will have access to mental health treatment and 200 more will have alcohol and drug treatment as a result of funding in Budget 2019.
The $128.3 million boost for offenders in prison and in the community is part of the $1.9 billion package for mental health and drug addiction services that was the centrepiece of last month's Wellbeing Budget.
Properly treating mental health and drug addiction conditions is considered a major factor in reducing reoffending; 61 per cent of prisoners are re-convicted of an offence within two years of being released.
This morning Corrections Minister Kelvin Davis and Health Minister David Clark visited a Corrections community centre in Upper Hutt to reveal further details of what the Budget money will be used for.
Once fully implemented, the expanded mental health services will support up to 2310 additional offenders with mild to moderate mental health needs every year.
"We know that 91 per cent of people in prison have a mental health or a substance abuse issue over the course of their lifetime so it's only right that we help them," Davis said.
"We want to lift the lid and the embarrassment that people have felt about admitting they have a mental health issue. It's so widespread that we just need to enable people to talk about their issues with confidence, and freely."
Davis said prisoners are eventually released and the ultimate goal was to make communities safer.
The Budget money will also be used to expand support for offenders' families; currently programmes support about 100 families a year, but this will be expanded to 275 families.
Alcohol and drug treatment in prisons will have four additional treatment programmes, treating 204 more offenders per year.
Additional support for offenders who have been released into communities included alcohol-detection bracelets to help people avoid drunk driving, and support workers offering support to prevent relapse.
Today's announcement also includes:
• An extra 25 mental health clinicians and 15 new support workers across prison and community sites.
• Supported living accommodation for up to 30 offenders a year with intensive mental health needs who are transitioning to the community.
• Social worker and trauma counselling services for up to 800 prisoners a year to help them reconnect with whānau and address personal trauma.
A recent report that spoke to thousands of people for their experiences with the criminal justice system found widespread frustration that the system did not treat mental health and drug addiction as a health issue.
Comments peppered in the report, conducted by the Safe and Effective Justice Advisory Group, found a lack of services across the sector.
"There are significant delays, about six to eight weeks, to get our young people mental health assessments," one person told the review.
"Often, they are waiting in prison for these. There is a major lack of resources including specialists."
The Wellbeing Budget included a number of packages to attempt to address the drivers of crime, including a $320 million package to stop family and sexual violence, and a $98 million package to help prevent Maori offending.
"We can't expect to reduce reoffending and see fewer victims of crime if we don't deal with the issues that landed people in prison or on a community sentence in the first place," Davis said.
"If we support people struggling with mental health or addiction issues, we make it easier for them to engage in education, employment and rehabilitation activities, and develop positive relationships with whānau and support networks."