Immigration and health services must do more to prevent ineligible foreigners ripping off the public health system, says an Auckland health chief.

Wayne Brown said yesterday that they had improved but more was needed although it was hard for hospital staff to confront patients - "they're not detectives".

"It's an ongoing battle. We've got better at it but it's a long way short of acceptable," said the Auckland District Health Board chairman. "We are improving links with Immigration, starting to get them aware there is a consequence of having people processed overseas."

Auckland's three health boards had non-resident bad debts totalling more than $5 million in the last financial year, but requiring new patients to prove eligibility is shrinking the problem significantly.

The Weekend Herald reported the case of a Chinese woman who received $51,189 of treatment at the Auckland board's facilities before being found to be ineligible for taxpayer-funded care.

The 66-year-old, on a temporary student permit, was treated in the blood and heart wards and at an outpatient clinic from August 2004.

To claim eligibility, she had used the passport of a dead person with a Chinese name who had left New Zealand in 2002.

A board audit department memo last month shows board officials were told about the patient by Immigration and were about to confront her. But the Labour Department, Immigration's parent agency, told the Herald the patient left the country the same day.

"The Chinese national ... departed New Zealand on 26 September," said group manager border security Api Fiso.

"[She] was required to undergo a full medical assessment when she applied for an extension to her permit earlier this year. A medical assessor determined the testing was clear and she was deemed to have an acceptable standard of health at that time."

Mr Brown said the case was a good example of how far people would go to obtain free treatment they were not entitled to.

He also highlighted the related problem of an applicant being declared fit overseas last year and then "miraculously" coming down with leukaemia, a $100,000-plus disease to treat, within two days of arrival.

"They had received their ... visa from an Immigration office in India.

"When somebody in India gets permanent residence and they arrive and get an expensive disease, I just don't accept they didn't know. I think that's fraudulent."

Mr Fiso said the Government had introduced several policies in recent years to tighten the health screening of temporary and permanent migrants. They were designed to minimise the costs to the state of migrants' health care.

He said health boards were responsible for charging ineligible patients but when possible the department helped with this if the patient was sponsored by an employer who accepted all responsibility when a work permit was granted.

The rules

* New immigration policy was introduced last November in an ongoing attempt to minimise the costs to the Government of migrants' health care.

* It directs anyone intending to stay in New Zealand for longer than a year to have a more extensive medical examination than previously required.

* New tests required include HIV and hepatitis and an assessment for critical developmental delay.

* Aim: to generally exclude those with conditions likely to impose significant costs (set at $25,000) or excessive demands on the health or special education services.

* For those seeking residence, but not a temporary permit, 10 conditions are listed as grounds for automatic exclusion, such as Alzheimer's disease, many cancers, heart disease needing invasive treatment and, in young people, severe visual or hearing impairment.