Counties Manukau District Health Board believes some non-resident Pacific people in South Auckland may be using false identities to get free healthcare.
The board was made aware of the issue through its community network. It believes some people could be using other people's IDs, such as relatives who are residents, to get access to health services.
Chief medical officer of health Gloria Johnson said this means the medical records of two different people, with different histories and health problems, may become confused.
Dr Johnson said that could lead staff to make the wrong decisions about someone's diagnosis or treatment.
She said the risks may continue in the long term, as it is hard to disentangle records.
Dr Jackson said the use of false identities can be hard to detect and it is often suspected when anomalies are detected.
