The detention of Kiwis living in Australia could be part of a push to "purify" the country, Labour's Corrections spokesman Kelvin Davis says.
Davis has hit out after new figures show the number of New Zealanders held in detention centres like that on Christmas Island at 199.
There are a total of 1577 people held, including 175 Iranians held, and 142 from Vietnam.
Davis questioned why many of the New Zealanders had to be locked up while they appealed their visa cancellation, and said it could be a policy to "purify" Australia.
"They are cleansing themselves of undesirables, even if those people have been born in Australia."
Many of the New Zealanders held in detention centres are of Maori descent, alarming the Iwi n Aus group and Maori Party.
Davis said he did not mean Australia was trying to get rid of Maori or Pacific Islanders.
"I just meant the cleansing of undesirables. A lot of those people are Maori and Pacific Islanders. That sort of raised my eyebrows, but I've got no evidence that that is what they are trying to do.
"But they are certainly trying to get undesirables out of there, even if they are products of Australia."
The New Zealand Government has boosted funding to Corrections and support services to try and settle deportees who are returned.
Prime Minister John Key hosted his Australian counterpart Malcolm Turnbull in Auckland last October, and pushed for the threshold at which Kiwis were deported to be softened.
That should be done in recognition of the special relationship the two countries have, Mr Key argued.
However, Mr Turnbull declined to do so, saying it was Australia's "absolutely legitimate sovereign right" to revoke visas should the holder commit a crime.
He promised to put more resources into the appeal process so it could be carried out more quickly, and to clear a backlog that had resulted from the law change in December 2014.
That allowed the Australian Government to cancel the visa of people who had been jailed for 12 months of more (cumulative), or failed a character test.But the number of New Zealanders held in detention centres has not declined significantly since then.
In October 2015 there were 213 Kiwis held, compared to the most recent number of 199.
People in Australian immigration detention as at June 30:
• New Zealand 199
• Iran 175
• Vietnam 142
• Sri Lanka 94
• China 87
• Afghanistan 66
• India 65
• Bangladesh 59
• United Kingdom 53
• Other 637