The corrections union is feeling left out following the Government's $1.9 billion boost for the sector.
Corrections Minister Mark Mitchell on Monday announced a plan which will see funding for more than 800 extra beds at Waikato's Waikeria Prison.
The Government also plans to deliver 700 new frontline staff and a $78 million investment in extending rehabilitation programmes for prisoners on remand.
However, Corrections Association president Floyd du Plessis said the union wasn't contacted prior to the announcement.
"The concern we've got is, at this stage, the announcements are just hollow announcements without any substance or detail behind them," he told AM.
"We do acknowledge that minister Mitchell did make contact with us yesterday after the announcement to let us know some of the thinking... but the [Corrections] department themselves have made no contact before this. They haven't sat down with us and just had a high-level discussion around what they're thinking and how this is going to work because that's the concern we have."
Du Plessis said there were parts of the proposal "we just don't feel" would work.
"Obviously, part of that announcement is the new Waikeria build - we've got serious concerns around that.
"Unfortunately, the Waikeria build has been marred with [a] lack of consultation up until now and the one area of serious concern for us is, while we welcome the idea of increased beds and the prison built in a better way... hiring staff in the Waikeria region is extremely hard. You're talking about a region that doesn't have a big population and this is going to be our biggest prison by far.
"There are not enough people that live there now and, even if you bring people into the region, there's not the housing infrastructure - so that is a serious concern."
A Corrections spokesperson said union wasn't consulted ahead of Monday's announcement due to "the confidentiality required for Budget sensitive information".
"Now that we have received confirmation of the funding received, we will engage with our unions on further decisions moving forward, including around the new beds at Waikeria Prison.
"Corrections is committed to keeping the public safe, reducing re-offending and giving people in prison every opportunity to turn their lives around.
"We welcome the additional investment, which will enable us to deliver more frontline staff, more prison capacity and extended rehabilitation programmes for remand prisoners."
The funding was earmarked to be rolled out over the next four years.
