Numerous investigations are underway into the suspicious deaths of five people at a Baptist-run aged care home in Queensland's northeastern Townsville.
Carinity says one of its own staffers raised the alarm last November, sparking the immediate removal of three registered nurses for failing in their duty of care at its Fairfield Grange home.
The nurses had been under the instruction of a doctor who is the subject of a report to the Queensland government's Office of the Health Ombudsman.
Carinity chief executive Jon Campbell has reassured residents of the home that they were now safe.
"Carinity removed any harm or potential for harm on 22 November last year," he said in a statement on Wednesday, also expressing deep sadness and sympathy for affected families.
"While the nurses acted within the doctor's direction, no system is immune from the ability of human beings to make inappropriate choices. We will continue to strengthen and improve our systems based on this experience."
Federal Aged Care Minister Ken Wyatt said he had asked the Aged Care Complaints Commissioner to urgently examine Carinity had taken appropriate actions.
"I am extremely saddened to hear of the deaths at Carinity Fairfield Grange and my thoughts are with families, friends and other residents," he said.
"The provision of safe, quality care is non-negotiable, and the health and wellbeing of senior Australians in aged care services is of paramount importance.
"Any abuse is unacceptable and the Department of Health is continuing to closely monitor the welfare of care recipients."
Two weeks after the nurses were sacked, assessors from the federal government's Australian Aged Care Quality Agency arrived to carry out a six-day audit of the home.
The deaths are the subject of ongoing probes by police and the coroner.
All five people who died had been receiving palliative care at the Townsville home.