Just eight people have had their refugee status revoked after a long-running saga involving a global people-smuggling ring which spirited hundreds of asylum-seekers into the country.
One of those who successfully appealed against the cancellation was identified in photographs as a high-ranking Afghan government official.
Evidence against him could not be shown to the tribunal governing refugee appeals because police lost the file.
For nearly a decade, Immigration NZ officials tried to cancel the refugee status of the asylum-seekers after a two-year police investigation codenamed Operation Amid.
The inquiry uncovered an Afghan-Iranian crime syndicate that smuggled hundreds of refugees into the country between 1995 and 2000.
The 7000 documents seized by police also indicated possible national security issues.
The asylum-seekers paid up to $30,000 each for forged papers to get them on a flight to New Zealand, where new identities and credit histories were provided by the smuggling ring.
Many destroyed their forged documents in flight and were granted refugee status on arrival, while others made it through border controls to start a new life.
A Department of Internal Affairs tip to police about possible passport fraud led to Operation Amid in 2000.
Search warrants on 20 Auckland homes and businesses uncovered documents that suggested the refugees had lied about their backgrounds.
A parallel police investigation, Operation Beaver, led to Sarwar Rahimi, his wife, Lida, and her brother Javed Ahmadi being convicted of using documents with intent to defraud in 2002. The trio admitted lying on their refugee applications.
Police did not press charges as a result of Operation Amid but passed the evidence to Immigration New Zealand, as the documents suggested 121 people obtained their refugee status fraudulently.
Insufficient evidence led Immigration officials to allow 98 refugees to stay but the refugee status of the remaining 23 was revoked. Half of those had links to suspected people-smuggling, identity fraud, marriage fraud, fraud, theft and serious assault.
Figures released under the Official Information Act show that 15 of those 23 who had their refugee status revoked were successful in appeals to the Immigration and Protection Tribunal. One of those who had his asylum revoked, who is known only as AF, was originally charged with lying on his refugee claim.
But police dropped the criminal charges because of fears he would not receive a fair hearing so soon after the September 11 attacks.
However, the evidence gathered against him was not able to be used in the immigration hearing because the police lost the file.
Included in the evidence were photographs identifying him as the Director-General of Borders in the Government of Afghanistan.
The Immigration and Protection Tribunal said evidence which was "of more concern" were documents seized by police that contained satellite telephone numbers which were used to infiltrate mujahideen groups.
"On balance, however, such 'intelligence' raises suspicions but no more than that," the tribunal wrote in its decision to allow the appeal.
"AF has not been charged with any offence in relation to this material and no security risk certificate was issued."
121 refugees suspected by police of immigration fraud
98 cases with insufficient evidence
23 refugee status revoked
15 successfully appealed