Whistle-blowing exploited migrant workers who are unlawfully in New Zealand may be able to escape deportation and apply for new visas under a policy review.
"Immigration recognises that migrant workers who have been exploited may be deterred from coming forward because of concerns about their immigration status," said Peter Elms, the agency's general manager.
"To address this, Immigration is undertaking a review of its operational policy to ensure that migrants who come forward to report exploitation are not disadvantaged by making their concerns known."
In the past year, 1045 deportation liability notices were served, including to those who reported employers who breached immigration laws but were unlawfully here.
Among them were 238 who had held a work visa.
Other reasons for deportation included breaching of visa conditions and changing circumstances that no longer met the rules or criteria under which a visa was granted.
"The exploitation of migrant workers is an extremely serious issue. Immigration will not tolerate employers who exploit migrant labour for their own commercial advantage and we will take swift action against those who are implicated in such behaviour," Mr Elms said.
He said employment advocate May Moncur claimed to be aware of 60 such casesthe agency was working with her.
Ms Moncur last month won a case at the Employment Relations Authority for a migrant worker from China, who was made to pay her own wages and taxes by an employer who promised to support her application for permanent residency.
At least three more cases with allegations of employers exploiting migrant employees on temporary visas are still before the authority.
Over the past 12 months, 33 cases of employers exploiting migrant workers were investigated, but employment advocates said this was just the tip of the iceberg.
Ms Moncur said it was "a step in the right direction" for Immigration to stop deporting informants if it was serious about investigating employers breaking immigration laws.
Rob Stevens, also a general manager at the agency, said under current policy a breach of visa conditions was grounds for making a person liable for deportation under the Immigration Act.
"For cases where visa holders have breached their conditions, but there is evidence of significant exploitation, such as serious breaches of Minimum Wage or Holidays Act, our approach will be to provide an appropriate level of up-front assurance for a person who proactively approaches a relevant agency with credible concerns," Mr Stevens said.
"The outcome of the intended approach will provide assurances with respect to both non-deportation, and non-prejudice of further visa applications."
Three Thai women, Kewalin Chunpoo, 37, Peeraya Sanmao, 40, and Onnicha Junlhon, 35, were granted visas this year after they blew the whistle on an immigration scam involving agents allegedly charging more than $10,000 for promises of residency and jobs, but obtained just holiday visas.
A woman was charged and the three were witnesses during a High Court trial. But they were made to leave the country last week after the trial was aborted on a legal technicality.
(Between Oct 1, 2011 and September 30)
33 employers investigated
238 work-visa holders served deportation notices
1045 total number of deportation notices served
$100,000 and/or 7 years' jail - max penalties for breaching Immigration Act