A "toxic" culture of cover up at the South Australian government-run Oakden nursing home was responsible for the failure to identify years of abuse of elderly patients with dementia, according to state and federal public servants.

The senior SA Health official responsible for the facility, Northern Adelaide Local Health Network chief executive Jackie Hanson, today fronted a public Senate inquiry into aged care accreditation standards, prompted by the abuse.

Ms Hanson was asked by senators to explain why the abuse was able to continue undetected for so long.

"It was a very closed environment. The wards were locked wards," she said.

Jackie Hanson said people did not complain because they were intimidated. ( ABC News )

"The clinical view from the staff working there was that it wasn't really a safe place or appropriate for too many visitors to enter because it stimulated the residents to the point they would get very upset.

"My personal opinion of that in my reflection of what I now know and what I've heard from meeting with staff and families, that closed environment was a very toxic environment, so people who worked there didn't recognise what they were doing or walked past it."

Ms Hanson told the committee she was not aware of the problems at Oakden until she spoke to family members of residents who had been mistreated.

"I asked them why they didn't complain - and they complained internally to the management team - and I think I'm not speculating when I say they were intimidated in relation to using any of the external agencies to make further complaints," she said.

"People who could have complained were intimidated."

Ms Hanson told the committee the Oakden nursing home facility received full three-yearly Commonwealth accreditation in 2010, 2013 and February 2016.

The relatives of the elderly people abused at the home are also giving evidence. ( ABC News: Nicola Gage )

The facility also passed an unannounced inspection by federal auditors in October last year.

"Although there were 44 standards and there was quite a lot of rigour on the surface around those standards, the process itself did not deep dive into individual care," Ms Hanson told the committee.

She said the Commonwealth audit process did not adequately include family members of the residents.

"They all without exception report observing the same issues, the same behaviours, the same treatment over many, many years. And if they had been involved in the accreditation process because the residents had no capacity, we would have seen a different outcome," Ms Hanson said.

"The buck stops with my position - with the CEO - and I've been on record in saying that."

The Oakden home was closed in September after a damning investigation by then chief psychiatrist Aaron Groves.

Commonwealth agency moves to unannounced visits

The Commonwealth agency responsible for the audits also gave evidence to the committee.

The Aged Care Quality Agency said audits included a requirement that auditors speak directly to at least 10 per cent of a nursing home's residents or their representatives.

But the agency's chief executive, Nick Ryan, baulked at suggestions from senators that the Commonwealth had failed in its responsibility.

"The fundamental failure rests with the provider," he told the committee.

Aaron Groves' report exposed systemic abuse and neglect of patients at Oakden dating back 10 years. ( ABC News: Nicola Gage )

"What happened at Oakden is absolutely unacceptable. Everyone involved in the Oakden facility and that includes myself as the CEO of the agency and my team will look for every opportunity and are already taking active steps that a facility such as Oakden is picked up next time and the abuse uncovered," he said.

Mr Ryan pointed out that it took South Australia's chief psychiatrist 10 weeks of observation to uncover the rate of abuse.

"There was complicit compliance going on in that facility. There was a culture of cover-up in that facility," he said.

He said the Federal Government was working on an action plan to approve accreditation practices and had made a commitment to move to unannounced visits.

"I accept responsibility that our system needed improvement and I've taken the active steps to deliver that," he said.

State Government 'confident' abuse is no longer occurring

SA Health told the Senate inquiry it was currently caring for 11 former residents of Oakden facility at nearby Northgate House until a new specialist facility was built.

"We are confident that the people who are residing in Northgate House are getting very appropriate care and we are confident that we will not open the service up again until we've got all the processes in place," Ms Hanson said.

She said the department had greatly reduced its use of restraints on residents with dementia.

"In the last three months we have probably had only six resident interactions that have not been appropriate. We have only one resident who has had one episode of restraint and that was at the request of his wife, and permission was sought from the Office of the Chief Psychiatrist," she said.

Dr Tom Stubbs, who is leading the Government's Oakden Response Oversight Committee told the hearing the department's use of restraint had gone from one of the highest in the country to "virtually nothing".

"That's a mixture of training, awareness, obviously a real focus on this at the moment. But the issue that I'm concerned about is that whatever we put in place is sustainable," he said.