New Zealand is using diplomatic channels to raise concerns with Australia over the deportation of a convicted criminal who has never set foot in New Zealand, Prime Minister Jacinda Ardern says.
But there is little else that New Zealand can do because Alex Viane, 40, is a New Zealand citizen, she added.
Viane was born in American Samoa and became a New Zealand citizen as a youngster, Fairfax reported at the weekend.
He went to Australia as a teenager on a temporary visa and has racked up several convictions and jail stints since then. His visa was cancelled on character grounds in July last year.
A decision from the Federal Court of Australia last week dismissed an application from Viane for a judicial review of his visa cancellation, Fairfax reported.
The decision included a handwritten application by Viane to revoke his visa cancellation.
"My parents are Australian citizens and I came to Australia with them in 1990 from Samoa," he wrote.
"I have no family or supportive networks in New Zealand. I have never been to New Zealand, I have no immediate family or support. I will have no hope of contributing positively to their society."
Viane has an Australian partner and a baby daughter, according to the decision.
Speaking on Newstalk ZB this morning, Ardern said Viane was a New Zealand citizen and Australia had the right to deport him to New Zealand.
But she said she had raised concerns with Australia.
"This is obviously someone who has never visited New Zealand, but has New Zealand citizenship. It's only right we ask questions.
"He is a citizen of New Zealand. My question is, is he a citizen also of the country he grew up in? That would have been the natural place you would assume he would be deported to.
"Australia is within its rights to do what it's doing. That's why we are using diplomatic channels."
Justice Bromwich, in the court's decision, said that Viane "will have access to similar social services and healthcare support as other citizens of New Zealand".
"I also find that after some initial difficulty, Mr Viane will have the opportunity to establish a lifestyle comparable to that of other citizens of New Zealand."
He added that Viane represented "an unacceptable risk of harm to the Australian community" and the protection of the Australian community "outweighed the best interests of his child and other minor family members".
Viane told the judge alcohol addiction had "caused all his troubles".
"I have never set foot in New Zealand and I am extremely concerned that if I am sent there, I will not be able to contribute to my daughter's or partner's lives."
Ardern has previously said Australia should only deport convicted criminals with genuine links to New Zealand.
"The point that we've always made is ... about making sure those who were only genuinely affiliated, and had roots here in New Zealand, were being deported.
"There are a number of contested cases where it is very clear that those individuals who are being deported actually have very firm connections, very firm roots in Australia."