A Bengali couple who ran a sweets making business in Auckland and paid their employees just $6 an hour have been jailed for their two-year exploitation of migrant workers.

Mohammed Atiqul Islam and Nafisa Ahmed were jointly charged by Immigration New Zealand (INZ) with several offences, including deceptively arranging the entry of two Bengali nationals into the country.

The pair, both New Zealand citizens, were also charged but found not guilty at a lengthy Auckland District Court trial of human trafficking.

It is one of only a handful human trafficking prosecutions in New Zealand's legal history.

Islam, a company director in his late 30s, was found guilty on 10 charges of exploitation and seven other immigration related offences.

Also known as Kafi Islam, he was also found guilty of three charges of attempting to pervert the course of justice.

Ahmed, an accountant in her mid 30s, was jointly found guilty of seven exploitation charges relating to five victims.

The pair's offending was uncovered after two of the chefs at the Royal Sweets Cafe, also known as the Royal Bengal Cafe, made complaints to New Zealand authorities about the conditions imposed on them.

The chefs' passports were also confiscated immediately after they arrived in New Zealand from Bangladesh after responding to advertisements in Bengali newspapers.

Judge Brooke Gibson said the chefs had "suffered grievously".

Working long hours, Islam and Ahmed's employees were paid just $6 an hour, were not paid for all of the hours they worked or holiday pay, the court heard.

Those on temporary visas were also encouraged by Islam and Ahmed to breach their visa conditions by working more hours.

Crown prosecutor Jacob Parry said some of the victims suffered swollen legs and hands and one thought "we might die from overwork".

"There is an attitude for the health of the business over the health of the workers," Parry said.

One worker had also said they even wouldn't have suffered such long working hours in Bangladesh.

Nafisa Ahmed and Mohammed Atiqul Islam listen as Crown prosecutor Jacob Parry address the court. Photo / Sam Hurley

Ahmed's lawyer, Ron Mansfield, said that a worker was fearing death was a "complete exaggeration".

He said the living conditions of the workers were far better than those of other comparable exploitation cases.

Steven Lack, the lawyer for Ahmed, said his client was less culpable because she was not as involved in the day-to-day running of the Bengali sweet-making business.

Both Mansfield and Lack called for sentences of home detention for the couple.

A pre-sentence report for Ahmed said she had not expressed a willingness to change and blamed the lack of payment on cash flow problems.

Judge Gibson, however, said Ahmed aided her husband's offending and her attitude displayed the couple's "arrogant and self-entitled approach to [their] employees".

"Neither of you take any responsibility for this offending, neither of you have any remorse," he said.

Both Islam and Ahmed, who have a young son together, were aware of New Zealand's minimum wage laws and were university educated people who worked in the country for several years, Judge Gibson said.

He said the evidence showed the couple's exploitation was "calculated and premeditated" and conducted for commercial gain.

It was a "selfish manipulation of people, largely from your own community", Judge Gibson said.

Islam was sentenced to four years and five months' imprisonment, while Ahmed was jailed for two years and six months.

After the verdicts, INZ acting general manager Jock Gilray said the case sent a strong message to the community that migrant exploitation would not be tolerated.

"Exploiting migrants is an abhorrent practice that undermines human rights and creates an uneven playing field for the vast majority of New Zealand business that seek to comply with New Zealand law," he said.

Faroz Ali, the first person convicted of human trafficking in New Zealand, pictured on during his trial. Photo / Pool

The first human trafficking charges in New Zealand were brought by INZ in August 2015.

Two men were charged for arranging by deception the entry of Indian nationals into New Zealand. However, they were both found not guilty of the trafficking charges, with one found guilty on other charges.

The first person to be convicted of people trafficking in New Zealand, Faroz Ali, was sentenced in December 2016 to nine years and six months' imprisonment and ordered to pay $28,167 in reparation to his victims.

Ali's lawyer, Mohammed Idris Hanif, was also later found guilty of knowingly providing false and misleading information to INZ which helped enable the human trafficking.

Hanif was sentenced last September to 10 months' home detention with six months' post detention conditions and ordered to pay reparations to the three Fijian workers who were exploited.

Last week Hanif was struck off the roll of barristers and solicitors by the New Zealand Lawyers & Conveyancers Disciplinary Tribunal.

Human trafficking is the second largest crime in the world and reaps billions of dollars in profits every year.

Lawyer Mohammed Idris Hanif outside the Manukau District Court. Photo / Greg Bowker