The leader of the Welsh Conservatives has called for a full inquiry into the NHS after a damning report into care at a mental health unit in Denbighshire.
Andrew RT Davies said assurances were needed that there could be no similar failings elsewhere after "institutional abuse" was found at the Tawel Fan ward at Glan Clwyd Hospital in Bodelwyddan.
Families described patients being treated like animals in a zoo.
Betsi Cadwaladr University Health Board has since apologised.
Mr Davies called on the Welsh government to establish a Keogh-style inquiry - set up following the Mid-Staffordshire Hospital scandal - and hold a "full and frank" debate in the assembly to ensure measures have been put in place to protect the NHS in Wales from a repeat of the problems at Tawel Fan.
"We have to have action to make sure this doesn't happen again," he told BBC Radio Wales.
"What I want to hear... is that there is now in place a process that will not allow this event to reoccur... and that people who have abused their positions of trust are held to account rather than being allowed to walk away from this or put into other positions".
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The independent investigation found
- Patients nursed on the floor
- A lack of professional, dignified and compassionate care
- Unsupervised patients
- An environment which does not promote independence, resulting in restraint
- Regimes/routine/practice on the ward which may violate individual patients' human rights
The Welsh Conservatives called for an inquiry into the NHS last year after problems were highlighted at 20 hospitals.
Deputy health minister Vaughan Gething said a series of spot checks across the NHS in Wales had since found a "very high level of care being the regular standard".
He said the "truly appalling" care at Tawel Fan was "just around the corner from an award winning mental health provision" on the same hospital site.
"That's what makes this truly shocking and hard to understand," he said.
Carol Anne Jones, of the Alzheimer's Society, said: "It's unbelievable that in this day and age that something so horrific has happened."
Betsi Cadwaladr University Health Board has apologised for the "inexcusable and unacceptable" treatment.
A spokeswoman said the health board "will be undertaking a full investigation into how this situation could happen to ensure we can prevent something similar in the future".
Tina Donnelly, director of the Royal College of Nursing in Wales, told Radio Wales there now "needs to be very high scrutiny" to make sure people put in place make "changes happen".
Eight members of nursing staff have been suspended on full pay and a "significant" number have also been transferred to other roles.
Others, including managers, have been "stood down".
North Wales Police carried out an investigation, but after consultation with the Crown Prosecution Service, it was decided no charges would be brought.
In the independent report, one family said it was like going into a zoo and seeing "captured animals".
Watchdog Healthcare Inspectorate Wales (HIW) admitted its own failings in the wake of the report, saying scrutiny at Tawel Fan ward "failed to detect and respond to the concerns at an early enough point in this case".
Ms Jones, of the Alzheimer's Society, added: "We've got to learn lessons from these horrific incidents and this shouldn't be allowed to happen again."