A national health insurance (NHI) scheme would threaten the excellence of South Africa's private healthcare sector, the SA Institute of Race Relations warned on Monday.

It would be problematic to introduce the scheme at a time when evidence suggested that the public health care sector was in disarray, the institute's deputy chief executive Frans Cronje said in a statement.

Fixing the management and other ills confronting public hospitals and clinics could do as much, if not more, to improve the healthcare services available to poor people than any NHI scheme.

Outlining the findings of a report by the institute's Unit for Risk Analysis, he said it questioned the financial feasibility of a NHI scheme.

It was conceivable that the cost could be as high as R465 billion a year if it sought to give all South Africans benefits on a par with those enjoyed by private medical aid beneficiaries.

This was obviously not affordable.

As just 11 percent of the population earned a taxable income, the economic impracticality of any scheme became even more apparent.

Countries with NHI systems tended to have high net incomes, low unemployment, and large and stable tax bases, which were not features of South Africa.

Cronje said the report found that only eight percent of the black population was covered by medical aid compared to 64 percent of whites.