Overseas visitors are putting their lives at risk by using New Zealand relatives' names to access free emergency hospital care, says acting Manukau Mayor Arthur Anae.
Mr Anae, who is also a member of Counties Manukau District Health Board, says at least two foreigners have narrowly escaped death as they tried to beat the system.
He cited one case in which a non-resident who required emergency care gave the name of a New Zealand relative.
Mr Anae says the patient's blood group did not match that on records of the person the patient had claimed to be, and if the hospital had not had those records, a tragedy could have easily occurred.
He says it was only when doctors performed checks that it was revealed the patient had had a previous operation.
Mr Anae is speaking out on the issue because he fears someone could be killed, and does not want doctors to be unfairly blamed.
He says compulsory medical insurance on arrival in New Zealand would help overcome the problem.
The Ministry of Health says it is aware of the problem but has had no official complaints from district health boards that it is a widespread.
It says health boards do their best to check people's entitlement to funded services, but staff often have to take information provided to them in good faith.