Allegations of an entrenched culture of bullying directed towards staff at a South Australian forensic mental health facility have sparked an independent review, with a public letter warning the situation at the site is now “dire”.

The letter, from “concerned staff” at Adelaide’s James Nash House, alleges that a “bullying culture” and “unprofessional behaviour” by certain staff within one of SA Health’s local health networks have driven away much-needed experienced workers from the secure facility.

James Nash House accommodates patients who are deemed by courts as not guilty, or unfit to plead, due to mental incompetence, and it also provides acute mental health care services for prisoners.

The facility at Oakden falls under the authority of the Northern Adelaide Local Health Network (NALHN) — a division of SA Health — and its chief executive Maree Geraghty said she had met with staff to assure them the allegations in the letter were being taken “very seriously”.

“It’s a very challenging work environment, and I’ve got the utmost respect for all of our staff,” she told ABC Radio Adelaide’s Stacey Lee and David Bevan.

The letter, addressed to the SA Premier and distributed to health authorities including SA Health and the Office of the Chief Psychiatrist, as well as to media, alleges staff have been “belittled, insulted, humiliated and constantly put down” by other staff members.

“When staff try to respond to the bullying they are further targeted until they have no option but to leave or retire earlier than preferred.”

It also alleged that those behind the culture “undertake to ‘get rid of’ staff they do not like” and that those impacted were forced to “remove themselves from this environment of bullying and targeting”.

“Poor working conditions are impacting on our health both mentally and physically. We have lost a high number of experienced and highly skilled staff as a result of this unprofessional behaviour,” the letter said.

“No matter how often we try as a staff group to address the bias, bullying and unprofessional behaviour within our ranks, nothing changes to improve the situation.”

NALHN’s chief executive said she first became aware of the issues when “the department of the Office of the Chief Psychiatrist rang me, and then the next day I received the letter in the mail”.

“We are doing everything we can to properly look at it,” Ms Geraghty said.

“We’ve worked to develop the scope of that review looking at all the matters raised in the letter … so looking at the quality and safety of the care that we provide, looking at the cultural issues.”