New Zealanders held in Australian detention centres without any indication of when they will be deported are frustrated and confused, a politician who has visited the centres says.
Australian Greens' immigration spokeswoman Senator Sarah Hanson-Young said the "desperation" of the indefinite nature of the detention was a problem.
"You've got to remember that people haven't been given sentences. They're there for as long as the Australian Government wants them to be," Hanson-Young told TVNZ's Q+A.
"It could be a matter of weeks, it could be a matter of months, it could, in fact, like it is for many, a matter of years.
"And of course the longer people are in these places, the worse their mental health gets. And that's what we've started to see."
Greens parties in Australia and New Zealand have jointly called on the Australian Government to stop the indiscriminate deportation of New Zealand offenders from Australia.
Hanson-Young said she had spoken with some of the New Zealanders held in detention centres, and said they were frustrated and confused.
"They believe they've done their time that they were convicted for by a judge in a court."
Australian Foreign Minister Julie Bishop met New Zealand counterpart Murray McCully and Prime Minister John Key in New York this week.
Afterwards, she said the Australian Government would talk further about its policy of detaining and deporting non-Australian offenders who have served a prison sentence of a year or more.
Around 200 New Zealanders are currently in Australian deportation centres, including on isolated Christmas Island near Indonesia.
Ms Bishop said she would ask Australian Immigration Minister Peter Dutton to speak to New Zealand Immigration Minister Michael Woodhouse but gave no indication that the policy would be reviewed. That meeting has not been scheduled.
Ms Bishop also said the New South Wales Police would investigate the death of Junior Togatuki, 23. Togatuki, who had mental health illnesses, died in solitary confinement in Goulburn's Supermax prison after having completed his sentence and while awaiting deportation to New Zealand.
Mr Key has said he believes the tougher policy is unsustainable, and that he had a "blunt" conversation with Ms Bishop.
However, the Government's response has been criticised as subservient and not nearly strong enough by its coalition partner United Future.
Marama Fox, co-leader of the Maori Party, is also pushing for more to be done, having been contacted by concerned families and groups.
"I think that he [Mr Key] should be bringing up our Anzac history, our closer relationship and not about economics.
"[Deportees] weren't criminalised in New Zealand - they were criminalised in Australia. And because of the new laws, they're going to throw them on a plane and send them home."