Indian nationals are being targeted in a scam where callers posing as immigration officials demand thousands of dollars, threatening deportation if the person doesn't pay.
The callers claim to be calling from Immigration New Zealand and tell the person there has been a problem with the processing of their visa or arrival card information.
They then demand money be paid into a Western Union account in India.
The callers were aggressive and authoritative, said the Ministry of Business Innovation and Employment, and often had details about the person they were speaking to, which made the call seem genuine.
Additionally, the scammers used a technology which allowed a legitimate phone number, such as the Immigration contact centre, to appear when the call was actually made from another number.
Immigration New Zealand has been aware of the scam since mid-2013, but a new wave of fake phone calls has prompted the ministry to give further warnings.
Immigration said they would never request money over the phone and told potential targets not to pay, no matter how important the caller sounded.
Those targeted were told to contact the police or report the call to Scamwatch.