The Corrections Association says prison guards taking bribes to smuggle cigarettes to inmates should join them behind bars.
Labour MP Kelvin Davis has supplied Newshub with a recording of a conversation he had with a whistleblower who says a small number of guards at two Auckland prisons will take in two packets of tobacco for $500.
"I just have to ring up and they give me a time to meet them… It's always $500 a time plus two packets of tobacco," the person says in the recording.
"At Serco at Mt Eden, I was paying a warden there to get smokes in. Just smokes though, but it's still $500 a pop. That's how much the screws, I mean the wardens, are asking for."
Mr Davis says he will be taking the evidence to Corrections Minister Judith Collins today.
The Corrections Association represents prison staff. President Alan Whitley says they have no tolerance for corruption in their ranks.
"There is no place for them actually working in the prison system. The only place for them in the prison system is in a cell."
Once a prisoner has got a guard to smuggle in contraband, they're considered compromised and a risk to the safety of everyone else working there.
"Once somebody starts bringing something in, they're got by the prisoner," says Mr Whitley.
"You don't want to be working next to somebody that's doing that in a prison, because you don't know what they're going to do. They make the place unsafe."
He wants Mr Davis to hand over the evidence to police so they can investigate the allegations.
"We've got staff that come to work every day in very trying conditions, and they do an incredibly good job."
Smoking was banned in prisons in 2011. Mr Whitley says there were fewer problems initially than expected, but tobacco is still a problem nonetheless.
"If you're in your cell at night during the lockdown period, you're not checked that often. If you're discreetly doing it in your cell, you could probably get away with it."
Smoke detectors don't always go off, having been disabled by the prisoners.
And some don't even need the real thing, opting to make home-brewed concoctions out of teabags.