The government admits it does not know how many migrants might have been scammed through one of its employer-worker schemes.
Hundreds of migrants have been crammed into homes and are living in squalor after paying tens of thousands of dollars to come to New Zealand, with promised jobs also nowhere to be seen.
Immigration New Zealand (INZ) has launched a review of Accredited Employer Work Visa (AEWV), with a support package for those falling victim unveiled on Wednesday.
The scheme allows employers to get accreditation to use the visa to hire migrants for up to three years. The support package includes temporary funding for accommodation and essential living costs for victims.
Exploited migrant workers will be able to apply for a further Migrant Exploitation Protection Visa (MEPV), giving them more time to find a job, alongside free job search assistance service.
Immigration Minister Andrew Little said about 250 exploited migrants had been allocated to the MEPB during an announcement from the Ministry of Business, Innovation and Employment's Christchurch offices.
When asked how many migrants had been exploited through the scheme, Little said he "couldn't quantify it".
"We know that the number of people who are currently on a Migrant Exploitation Protection Visa is roughly 250.
"Not every migrant worker who claims exploitation goes onto the Migrant Exploitation Protection Visa.
"So I expect the number who have experienced some form of exploitation will be bigger than that."
INZ's processes around the checks and balances of the scheme have come under the microscope, with a review under way into how it has been rolled out.
Little said immigration rules were being strengthened and he promised better checking of prospective employers and individual job checks. Furthermore, 90-day trial periods are also being removed for accredited employer work visas.
"Too often, recently, we've seen migrants arriving and starting work, only to be dismissed within days," Little said.
The minister said people who were considering a move to New Zealand needed to be wary.
"Watch out for the scams.
"If you are paying tens of thousands of dollars in order to come to work here, you are being scammed, that is not what it costs to get a visa to come here, so be very careful."
A migrant worker advocate welcomed the support package, but there were still concerns. Bangladesh Skilled Migrant Association New Zealand secretary Faisol Miah said the six-month period for the MEPV may not be long enough for migrants to secure work.
"They may not be able to get any job within six months.
"I'm a self-employed contractor I don't see many jobs here at the moment, I don't think six months is enough."
Miah said many exploited migrants were still in a state of shock over their situation.
"They just want certainty over the job [situation] ... they're worried over this."
INZ is expected to complete the review by December.