A review of the Accredited Employer Work Visa scheme was conducted by the Public Service Commission. It found the scheme, established once borders reopened, led to migrants being able to buy jobs and then being exploited on arrival.
The scheme was brought in under the Labour government.
Labour leader Chris Hipkins told Morning Report the government, and officials, were under pressure to get workers back into the country after the Covid shutdown.
"We were, at the same time as implementing a new system, putting them under enormous pressure to get things moving at the border more quickly."
While the overall approach and design of the system was right, there were "significant issues" with its implementation, Hipkins said.
"Politicians of all colours, including the current government and the previous government, put enormous pressure on Immigration New Zealand to get the border reopened quickly after the global pandemic and clearly I think mistakes were made in the process."
He said politicians had to accept a share of responsibility.
"The intention of the Accredited Employer Work visa was to drive out migrant worker exploitation. Details in the way it was implemented meant that it actually had the reverse effect and that was never the intention of the scheme."
The report also said multiple staff members raised concerns which were ignored by management.
"I'm extremely concerned about a number of the issues that have been raised in this report. We are clearly going to put a plan of action around each of the recommendations and we'll work hard to fix those issues.
"Clearly we have had a lot of discussion about the issues, the review focused on the operational implementation, the employment matters are separate, alongside that if any need to be acted on."
Tremain said initial concerns raised by staff about exploitation were too general to act on.
Tremain said 174 investigations were under way, and one licensed immigration advisor was currently facing prosecution.
Of the 33,000 accredited employers, post-accreditation checks had been conducted on 2700.
Some 145 had had accreditation revoked and 53 were suspended.
"Absolutely migrant exploitation should not be tolerated.
"What we have here is 33,000 employers who have been accredited, the vast majority of whom are good employers."
