Immigration NZ has launched a major investigation after 115 migrants from India and Bangladesh were found living in overcrowded and unsanitary conditions in six houses across Auckland.

They arrived in New Zealand under the Accredited Employer Work Visa scheme, which already has 164 active investigations after complaints of worker exploitation and breaches.

Meanwhile, Immigration Minister Andrew Little has ordered an urgent independent review of how the scheme is being operated after “serious concerns” were raised by a whistleblower on Tuesday that checks of potential accredited employers were not being carried out.

The Accredited Employer Work Visa scheme, established in July last year, has approved nearly 81,000 visas among about 27,900 accredited employers. It was meant to counter exploitation by ensuring employers were viable and treated their employees fairly, with pre- and post-accreditation checks.

But critics say the fact it ties employees to employers for up to three years and exempts them from paying the median wage leaves migrants open to exploitation.

Little said he still had confidence in the scheme but had sought confirmation through the Parliamentary Services Commissioner Peter Hughes about the accreditation and job check processes.

“These are serious concerns,” Little said in a letter to Hughes.

“At a high level, the concerns relate to how the scheme is being administered by Immigration New Zealand, potentially resulting in opportunities for misuse and exploitation by third parties.”

The Herald has reported extensively on issues with the visa scheme and concerns from immigration advisers and migrants who have been victims of exploitation, along with migrants being “sold” work visas overseas.

An Immigration NZ spokesperson said they had spoken with the 115 Indian and Bangladeshi migrants and found they had come to New Zealand with the promise of employment when they arrived.

“Individuals have indicated they paid a substantial amount for the visa and a job, yet most are still waiting for any paid work.

“These individuals were accommodated in properties that were not fit to house so many people. The conditions of the accommodation were unhygienic, unsanitary and inappropriate.

“Some individuals have been in New Zealand for several months and some have more recently arrived.

“Investigations into the employers who brought the individuals to New Zealand continue but we can advise that there are several people and companies of interest pertaining to this case.

“Our first priority was to ensure the health and wellbeing of all these individuals which included ensuring each property had food, water, electricity, as well as connecting them with local agencies who can provide pastoral care and support.”

The investigation would include speaking to witnesses and the Indian High Commission had already been involved.

The Ministry of Business, Innovation and Employment (MBIE) - which includes Immigration NZ - was working with the individuals to help them understand their options. This could include applying for a Migrant Exploitation Work Visa, obtaining employment with a new employer, or making suitable arrangements to leave.

INZ was also contacting offshore visa holders linked to the case to notify them not to travel until they received further contact.

MBIE chief executive Carolyn Tremain said they supported the independent review and it was important to remove any opportunities for migrant exploitation.

“We are committed to improving any policies and processes deemed necessary.

“The outcome of this review will allow us to further refine the [accredited worker scheme] and inform settings to better respond to emerging issues.

“While the review is being carried out, we will continue our work, including the processing of applications and responding to cases of migrant exploitation as a priority.

“Our people take great pride in their work and do this professionally whether that’s processing visas or carrying out checks.”

The scheme had allowed the country to reopen the borders and bring migrants in to support industries that needed them, Tremain said.