Prime Minister John Key says he's been "pretty blunt" with the Australian government over the way New Zealanders are being detained and deported.
Mr Key met Foreign Minister Julie Bishop in New York on Tuesday to raise the issue that's causing increasing concern across the Tasman.
Nearly 200 New Zealanders are being held in detention centres in Australia facing deportation under new immigration laws that mean anyone who isn't a citizen and who has served a sentence of 12 months or more can be sent home.
It's been reported that nearly 100 have already been sent back to New Zealand.
"I had a chat with Julie about it and I was pretty blunt," Mr Key told Radio New Zealand on Wednesday.
"I said there's a special relationship between New Zealand and Australia and you challenge that, to a degree, when you see New Zealanders being treated in this way."
Mr Key said some of them had spent almost their entire lives in Australia, having gone there when they were very young.
"We also deport people, but not in the way the Australians are talking about," he said.
Mr Key says it will be one of the most important issues he raises with Prime Minister Malcolm Turnbull when they meet.
A date for that meeting is still to be set.
The meeting with Ms Bishop took place amid growing calls for the New Zealand government to take action, following the death two weeks ago of Kiwi-born Junior Togatuki in a high-security detention centre while he was awaiting deportation.
The 23-year-old, who left New Zealand at age four, had served his sentence for robbery and assault, and authorities say he took his own life.
Ms Bishop has provided assurances to New Zealand that a full inquiry is under way into Togatuki's death.
Ms Bishop later told reporters in New York she and Mr Key had discussed generally whether the two countries could reach other arrangements.
"I think it would be timely for Prime Minister Turnbull to discuss this with Prime Minister Key," she said.
"There is no closer relationship than Australia and New Zealand, and so I think it's appropriate that we consider this matter."
