Some patients at Waitakere Hospital would in future be charged for their treatment, under a plan for private-sector doctors to set up shop inside the facility.

If approved, the scheme would lead to patients who refer themselves to the hospital being either treated free in the emergency department or sent to a new accident and medical centre.

In the latter case they would most likely be subject to the existing range of patient fees in West Auckland: from free for children under six on weekdays to $90 overnight on public holidays for unsubsidised adults.

The scheme, already in use at two rural hospitals, has been mooted by primary health organisation HealthWest. It is partly in response to the Waitakere Hospital emergency department still being closed to new patients from 10pm to 8am more than a year after the completion of the facility's $60 million upgrading to general hospital status.

HealthWest says the scheme would make it financially viable to have the emergency department's front doors open overnight.

The Waitemata District Health Board says it has to ration money and other service improvements are of higher priority. Its officials are writing an efficiency plan for the hospital and as part of that they will consider the HealthWest proposal.

A leading emergency medicine specialist, Dr Peter Freeman, said there was merit in having an accident and medical clinic next to an emergency department, but he did not favour having one inside.

Nor should patients have to go through a clinic's triage assessment process before they could enter the emergency department as it put at risk those with possible symptoms of serious conditions.