New Zealand has an estimated 600 people living in some sort of slavery, according to a report by campaign group Walk Free Foundation.
The anti-slavery foundation has released its Global Slavery Index which says nearly 36 million people are enslaved worldwide, two-thirds of them in the Asia Pacific region, Radio New Zealand reports.
Mauritania and Uzbekistan had the highest proportion of its population in modern slavery, at 4 per cent and 3.97 per cent respectively. It was followed by Haiti, Qatar and India.
New Zealand ranked fourth best of the 167 countries surveyed but experts warn there is no room for complacency.
Fiona David, a spokesperson for the Walk Free Foundation, said the cases in New Zealand included two men who were charged earlier this year with arranging by deception the entry of 18 Indian nationals in New Zealand. The men have denied the charges.
The Government has already changed labour laws to apply to foreign fishing vessels, and plans to introduce tougher penalties for employers who exploit migrant workers, among other changes.
The Walk Free Foundation report placed New Zealand second in the region when it comes to government action on slavery, but the country got five out of 12 for central government coordination and accountability.