A cross-party working group is finalising draft legislation that it intends to release for public consultation as early as next month.

The group hopes to introduce its bill into the NSW Upper House for consideration in the second half of 2017 at which point MPs from all major parties would be granted a conscience vote.

However, in an early indication of the challenges facing the bill, Premier Mike Baird and Opposition Leader Luke Foley told Fairfax Media they are personally opposed to changing the law and would not vote for change should it make it to the lower house.

Mr Baird said he recognises the passion of advocates of assisted dying legislation.

"While I fully acknowledge the sincerity of those who support change, and the terrible pain that is suffered by many terminally ill people and their carers, I myself will not support any change to the law," he said.

Mr Baird said an experience with a constituent early in his political career had offered him some insight into the issue.

"The complexity of this issue was brought home to me when I was door knocking in my electorate some years ago, and was kindly invited inside to talk with a couple who were dealing with horrendous circumstances, involving terminal illness," he said.

"While this hasn't changed my mind, it has given me a clear understanding that there are two sides of this issue, and that all views deserve respect."

Mr Foley said he would also vote against an assisted dying bill brought before the Legislative Assembly.

"I worry about the message it sends to a society where some old and frail people feel that they are too much of a burden on their loved ones, that they have to end it all," Mr Foley said.

But in a statement the working group said: "Law reform on the issue of assisted dying is necessary.

"The prolonging of pain, suffering, and distress, for both the terminally ill and their families, is not necessary; the fundamental principle behind the call for legislating to allow for assisted dying is to provide dignity to people who wish to pass peacefully and on their own terms."

Finer details of the bill are being kept under wraps, but Fairfax Media has confirmed it will not apply to those under 18 years old and only to the terminally ill.

Two doctors would have to agree and the person would need to be of sound mind and capable of giving consent.

The working group is comprised of Nationals MLC Trevor Khan, Greens MLC Mehreen Faruqi, Labor MLC Lynda Voltz, Liberal MP Lee Evans and independent MP Alex Greenwich.

Ms Voltz confirmed a draft bill was with parliamentary counsel and the intention was to release it for public discussion as early as next month.

"That will allow us to address any issues raised before the bill is introduced into Parliament sometime later this year," she said.

Mr Khan's late father was incapacitated by a stroke and while he was still capable of speech asked his son to help him die.

During a speech to Parliament last September, Mr Khan asked: "What is the difference between allowing a terminally ill person to die naturally by abstaining from treatment; and allowing them to die through means of voluntary assisted dying?

"Both are aimed at reducing suffering; both are aimed at providing dignity in the final days of one's life; both have the same reasoning, intention and outcome. Both should be legally permitted."

Mr Evans, the member for Heathcote, said he became involved in the group  because his mother suffered from dementia for nine years.

He said those who provided her with palliative care were "fantastic".

But he said: "At the end it was not pretty; she never wanted to end up like she did but there was no option."

Mr Evans said the group expected criticism about "knocking people off" but that he and his colleagues wanted to foster open and informed debate.

The proposal comes just months after a voluntary euthanasia bill was narrowly defeated in the South Australian Parliament and as the Victorian Parliament prepares to consider its own legislation in the second half of 2017.

Significantly, Victoria's Labor Premier Daniel Andrews is backing the legislation. Mr Andrews changed his mind on the issue after the death of his father in early 2016.

The Australian Medical Association opposes legalising voluntary euthanasia. But in a policy statement released in November, the association stipulated: "If governments decide that laws should be changed to allow for the practice of euthanasia and/or physician-assisted suicide, the medical profession must be involved in the development of relevant legislation, regulations and guidelines."

AMA NSW branch president Brad Frankum supported the policy statement.

"The primary aim of doctors should not be to hasten death but improve quality of life," Dr Frankum said.

"We feel that in the vast majority of cases adequate and timely palliative care is an appropriate way to treat people with terminal illnesses, accepting that it is not always perfect," he said.

A recent survey of AMA members found 38 per cent were in favour of doctors being involved in physician-assisted suicide, and 12 per cent were undecided.

But the majority of respondents said if voluntary euthanasia was legalised doctors should be involved in assisting terminally ill patients end their lives rather than boycott the measure.

Victoria's draft bill proposes access to voluntary euthanasia for adults of sound mind in the final weeks or months of life who were suffering from a serious, incurable condition.

The request would have to come from the patients themselves, and be repeated three times, including a formal written request and approved by two doctors who would be legally protected.

Doctors would prescribe a lethal drug that would be taken by a patient.

Public polling has consistently showed the majority of Australians were in favour of voluntary euthanasia.

A Newspoll survey conducted in October 2011 found 77 per cent of Australians believe it should be legalised, with 18 per cent not supportive.