John Key says he's been given assurance from Australian Prime Minister Malcolm Turnbull, that his minister will be reasonable when it comes to reinstating detained Kiwis' visas.
Mr Key says the situation is looking more hopeful for detained New Zealanders, after Mr Turnbull told him the process would be reviewed.
"There is an… authority for the minister to reinstate your visa. So it's automatically taken off you if you've served a sentence of 12 months or more," he told the Paul Henry programme.
"Of the people that have appealed – like pretty much everyone's appealing, that's why they're in these detention centres – a third of them have had their visa reinstated. They're reinstated for the reasons that I've been arguing – their family's there, they've lived there a long time, [and] their conviction is not of the most serious order."
Meanwhile, Labour MP Kelvin Davis is on Christmas Island where more than 40 Kiwi detainees are awaiting deportation. He says conditions for the detainees are not good.
"They're in a compound with high fences and razor wire, they're locked up in their compounds for most of the day, allowed out for a couple of hours each day," he says.
"It's stinking hot over here, so I think inside they've got a bit of air conditioning, and outside… they really just sit around and get bored and twiddle their thumbs."