There could be thousands of immigrants being abused at work but the government is unwilling to pay to root out modern-day slave-traders, an immigration adviser says.
The country's first conviction for human trafficking came last month when Faroz Ali was found guilty for his part in helping 16 Fijian workers enter the country illegally.
Ali's victims had to borrow hundreds of dollars from family and friends to pay him and his accomplices 'administrative and filing fees' for the chance to work on New Zealand orchards.
But when they arrived in New Zealand, they often had to sleep on the floor and were paid just a fraction of what was promised. At least one left New Zealand owing money.
Other immigrants have come forward with stories of having to pay their wages back or pay up-front for a job offer to get support from an employer for their visa.
Laurent Law consultant, Bill Milnes, said Immigration New Zealand was restricted to pursuing 'low hanging fruit', which did not include the scam perpetrators.
He said he suspected last month's prosecution would have cost many hundreds of thousands of dollars because of the complexity of the case and trips to Fiji to collect evidence.
He did not expect there would be any similar court cases in the foreseeable future without public pressure.
"Unfortunately, the resources that would be required for government to seriously tackle the involvement of gangs and criminal organisations in today's version of slavery are beyond the willingness of our politicians to commit to.
"Consequently, in my opinion, it seems that the compliance section of Immigration New Zealand is restricted in its ability to take action, to chasing cheap and easy cases, such as deporting the victims, the people who have already been most damaged by the traffickers and the 'employers' of the slaves in NZ.
"I've had clients who have had to buy job offers - which we have found out in due course down the track, not at the time. So it's a huge situation, a huge problem."
Immigration New Zealand assistant general manager Peter Devoy said it received 1800 allegations in the last two years of immigration-related offending which included people trafficking and exploitation.
Of those it had undertaken 60 prosecutions, although only two of those were for people trafficking.
"Since 2014, INZ has established both the Serious Offences Unit to combat top tier immigration offending such as people trafficking and the Employment Investigation Unit to monitor, investigate and prosecute immigration offences by employers," Mr Devoy said.
"Over the past year, two people trafficking trials have been brought to court by INZ with New Zealand's first ever successful conviction for people trafficking secured last month.
"The prosecutions send a very strong message that cases of alleged people trafficking or exploitation will be thoroughly investigated and legal action taken when there is sufficient evidence.
"Our whole-of-government approach recognises that prevention, detection and investigation, prosecution and compliance and victim support and protection are critical elements of a comprehensive approach to combating all forms of trafficking in persons.
"INZ remains alert to the possibility of people trafficking occurring and we have support mechanisms in place for any victims identified.
"We work closely with those non-government organisations which are likely to deal with potential victims of trafficking to ensure a joined-up approach to victim identification and support. This partnership approach recognises the important role that our communities play and the value of government and non-government collaboration."