A profiling programme labelled racist by critics has already been used to deport overstayers deemed to be "high priority", Immigration New Zealand has confirmed.

Immigration has been using the pilot for the past 18 months to analyse age, gender and ethnicity of overstayers to identify groups likely to run up hospital costs or commit crime.

Melino Maka from the Tongan Advisory Council said the pilot was racist and fears Pasifika people could be unfairly targeted.

Immigration Minister Iain Lees-Galloway - who did not know about the pilot until Morning Report told him about it yesterday - said officials assured him it was not racial profiling.

Mr Lees-Galloway is expecting to get a full briefing on the data modelling pilot today.

Immigration New Zealand assistant general manager Peter Devoy said the minister was not briefed initially because it was mainly an operational matter.

"It is important to stress that all decisions on deportations are lawfully undertaken by appropriately warranted immigration officers who look at various information sources as part of their assessments and prioritise accordingly.

"Individuals' human rights are not affected as any one served with a deportation notice still has appeal rights until they are deported from New Zealand," Mr Devoy said.

Immigration NZ said it had not evaluated the total number of people deported using the pilot - but did say it was certain there had been what the department called "high priority" deportations as a result of the modelling.

Human Rights Commissioner David Rutherford said such practices can raise very serious human rights concerns.

"We're concerned to ensure that agencies involved know that algorithms can discriminate ... and therefore there is a danger, so there needs to be ethics and human rights frameworks in place to deal with that."

Mr Rutherford is seeking further details about the processes and systems from the Ministry of Business, Innovation and Employment (MBIE), which is Immigration's parent ministry.

Privacy Commissioner John Edwards is also seeking more information about the pilot.

"You'd expect that a very robust process has been through to test the assumptions underlying the tool before it was deployed, so that is something I am looking forward to discussing with Immigration."

Mr Edwards said the pilot could actually be less biased than human decision making but not enough was known about the type of modelling being used.

With data modelling changing at a fast rate it could be a good time to check our laws still safeguard people's rights, he said.

"Our current laws do a pretty good job, they do require that administrative bodies making decisions adhere to the rules of prejudicial fairness and natural justice, that's a requirement of the Bill of Human Rights.

"That sits there in the background guaranteeing that people are not arbitrarily deported or arrested just based on anonymous data analysis," Mr Edwards said.

Green Party immigration spokesperson Golriz Ghahraman said she had written to the minister expressing concern about the programme.

"We've been working with the government to stop this kind of thing, people should not be targeted on their race to be identified as a risk, I've written to the minister and I've been speaking to the justice minister about it as well."

Justice Minister Andrew Little was not available.

The previous Immigration Minister, National's Michael Woodhouse, would not answer questions about the pilot, saying it was a matter for the current minister.

(Source: RNZ, Sally Murphy)