Former aged care minister Ken Wyatt signed off on new regulations in April to limit the use of chemical and physical restraints by aged care providers.

Before, the use of restraints such as sedatives or isolation had been occurring unregulated.

But public advocates are concerned the rules do not adequately protect the human rights of elderly residents.

For example, the principles allow medical or nurse practitioners to prescribe chemical restraints if the patient's "representative" has been informed.

They also allow aged care providers to use physical restraints so long as an approved health practitioner believes the person is at risk of harm, all other alternatives have been canvassed and it is the least restrictive form of restraint possible.

But a letter from public trustees and guardians from the ACT, Victoria, Queensland, NSW, South Australia and the Northern Territory to the parliament's joint committee on human rights said the new rules were a "flawed and ambiguous substitute" for making decisions about the use of physical restraints.

The advocates were also concerned it provided "virtually no regulation of chemical restraint usage".

"In particular we are concerned that the new principles have been introduced through a ministerial instrument rather than in legislation and that the principles appear to ignore Australia's human rights obligations under the United Nations Convention on the rights of persons with disabilities," the letter reads.

ACT public advocate Jodie Griffiths-Cooke, who signed the letter, said the rules set a significantly lower bar than similar standards in the disability sector "despite an equivalence of vulnerability".

She said there was a "lack of oversight and lack of line of sight" for the use of restraints in aged care, which meant it was unclear how widespread the practices were.

"One of the key issues is no one at the Commonwealth or local level has a record of the number times these practices are used in aged care, where as in the ACT disability space we have the Office of the Senior Practitioner and a new Act which requires all instances or planned uses of restraint have to be advised," Ms Griffiths-Cooke said.

Restrictive practices ranged from locking a person in a room by themselves, or using sedatives to curb violent behaviour.

It could even be the prescription of anti-libidinal medication to reduce sexual behaviours, Ms Griffiths-Cooke said.

"All behaviours exist for a purpose, they don't just emerge, the person is responding to things happening in the environmental around them," she said.

"A good provider would be going, hey we don't want this person getting upset, how can we create a calm environment, how can we ensure staff understand what upsets them, and now we've tried everything else first, restraint is absolutely necessary to protect themselves and others."

Queensland public advocate Mary Burgess said the new rules appeared to "drastically regress" protections for people living in aged care, whether it was an older person or a young person with a disability.

"While the Commonwealth should be applauded for recognising this critical need to regulate such practices in this sector ... the new law creates many more problems than it solves," Ms Burgess said.

Human Rights Watch told the committee Australia should be working to end the use of all forms of restraint as a means of managing or disciplining older people in aged care.

It has catalogued cases of overmedication in nursing homes in the United States, where anti-psychotic drugs were given to residents with dementia for reasons of convenience.

"Medicines should only ever be used for therapeutic purposes and with the free and informed consent of the person receiving them," the group said.

The use of antipsychotic drugs on older people with dementia is associated with a nearly doubled risk of death and other adverse reactions including stroke, falls and the inability to stake awake long enough to eat or spend time with loved ones."

The legal committee will hold a one-day inquiry into the issued raised by the public advocates on Tuesday.