Samoa tops the list of countries with citizens who have committed immigration fraud in New Zealand.
Twenty-two people from the Pacific nation have been convicted in the past 10 years of using fake immigration documents. That's 15 per cent of the 145 successful prosecutions.
India was second on the list with 13 convictions, followed by Somalia and New Zealand with 11 convictions each, then Fiji with eight.
The figures, released under the Official Information Act, show just one conviction against citizens from far-flung countries such as Tuvalu, Ghana and Bulgaria.
Of the 145 convictions, 128 were for "false documentation", where an individual uses fake papers to obtain a passport, the bio page or photo in a passport has been swapped, or the passport is a complete forgery.
Seventeen convictions were for "falsely obtained genuine documentation" where the passport is genuine but has been obtained by fraud.
However, Immigration New Zealand did not say how many of the 145 immigration fraudsters had been deported. The acting general manager of intelligence, risk and integrity, Peter Elms, said the information was too difficult to obtain as it would require a detailed search through each of the 145 cases.
Mr Elms said Immigration NZ received 70 allegations of fraud each month.
The longest sentence for an immigration fraud conviction was two years and nine months, given to Sahra Ismail in 2011.
Ismail came here in 2002 as a Somali refugee and was later granted New Zealand citizenship. But she travelled here on false names and documents, as she was already a refugee and citizen of Holland.
She had lived there for up to 12 years but efforts to have Ismail's family join her were thwarted by Dutch authorities.
Ismail successfully applied in 2004 to have seven family members join her as refugees.
The cost savings from preventing fraudulent secondary migration - where a principal applicant acquires residence and helps other family members in - are significant. "It has been estimated that on average each refugee fraud conservatively costs the Department of Labour $28,550," a 2010 report said.