When an Australian state health minister toured an urgent care clinic, she saw how busy staff treated patients in crisis -- one rushed in by ambulance, another lying injured on a trolley.

But all was not as it seemed during Victoria Health Minister Mary-Anne Thomas's visit last year to the clinic in the Colac heath area, southwest of the state capital Melbourne.

But things were apparently not busy enough.

So "approximately 10" local health staff posed as patients and sat in the waiting room, said an independent investigation into the August 9 visit released Wednesday.

In addition, "at least one ambulance" happened to arrive during the ministerial visit "containing an individual who posed as a patient" despite not needing treatment, it said.

One area health worker "who had presented with an injury but who was not actually seeking medical treatment, occupied a trolley in the back corridor", the probe by Wise Workplace Solutions found.

After the visit, the pretend patients' registrations in the system were cancelled and they left "without any treatment being administered".

Victoria's health department said the incident was "inappropriate".

"Individual action has not been recommended by the investigators for those who posed as patients," it said.

"However, all staff will be counselled on the seriousness of the matter and reminded of how they can speak up and of their responsibilities."