If health workers can do something like this they can pull off false flags easily.

Health workers posed as patients in a waiting room, arrived by ambulance and lay on a trolley in a corridor feigning illness during a ruse to make a regional clinic look busy for a ministerial visit.

About 10 staff posed as patients at Colac Area Health's Urgent Care Centre in August 2023, a Victorian Health Department probe has found. The investigation determined there was a "real possibility" that patient care could have been impacted during the charade which was intended to deceive Health Minister Mary-Anne Thomas into believing the centre was busier than it actually was.

Those who took part in the subterfuge won't be reprimanded but the organisers could be disciplined.

The person who arrived by ambulance was triaged despite not needing treatment, with fake patients registered in the clinic's records before the minister arrived and removed after she left.

Staff working in the clinic that day were found to be "generally aware or soon became aware" of the pretence and went along with it as they thought the health service expected them to.

Every fake patient had varying degrees of involvement and those who took part were asked to do so, the investigation found.

Ms Thomas said she was disappointed and didn't notice anything unusual during the visit.

"I had no reason to think that anything was untoward," Ms Thomas told reporters on Wednesday.

"It's certainly not something that ever crossed my mind."

The minister said the participants were "enlisted by some management staff" and she did not believe the scenario had been repeated at other health facilities.

"This type of behaviour is completely unacceptable to me, as it is to them," she said.

The probe recommended the fake patients who were drafted to play a part in the sham should not face disciplinary action, which the department agreed to.

However, those who organised it could face consequences.

The department said it does not have authority to take employment action against them, however the health service has been asked to review evidence to determine if they should be counselled, have further training or face disciplinary action.

Premier Jacinta Allan said the investigation's findings were still being reviewed when asked why heads were yet to roll over the stunt.

"It's just not acceptable to admit fake patients to make a political point," she said.

The investigation also recommended the health service do more to ensure a safe culture where people can speak up.

The incident was first raised by a whistleblower and some staff only co-operated in the department's probe on the condition of anonymity.

Colac Area Health interim chief executive Steve Moylan described the incident as highly regrettable and apologised.

"Colac Area Health is committed to learning from this incident and to keep building a better health service for our community, including by acting on the recommendations to strengthen our internal culture and also consider any further action," he said.

Ambulance Victoria's internal investigation into the involvement of the ambulance is underway.

Ms Thomas said the full health department investigation had not been made public because it named many staff members.

However, Opposition Leader John Pesutto said there was no reason the full report could not be released.

"If there's been wrongdoing, of course, there should be disciplinary measures imposed.

"Anyone who's involved in using health resources for any other purpose than the provision of health care for patients should face appropriate levels of disciplinary action," he said.

Colac Area Health covers about 30,000 people in the Corangamite, Colac Otway and Surf Coast Shires.

Australian Associated Press