The government had planned to ban smoking at the Canberra Hospital's adult mental health unit, as part of a broader move to stamp out smoking at all ACT Health campuses.

The ban was reportedly set to come into force from January 1 but the government was yesterday unable to confirm details of the plan, including whether that date was still accurate.

The move was designed to protect health staff, patients and members of the public from second-hand cigarette smoke.

But the Canberra Mental Health Carers Network has warned that enforcing an outright smoking ban on those with mental illnesses at a time of psychological crisis would exacerbate their conditions, with potentially damaging effects.

Mental health carer Philip Bell wants the proposal thrown out, claiming the government's consultation process has been a joke. He said during a mental health crisis was ''the very worst time'' to be trying to prevent people from smoking.

''When people are taken in for involuntary treatment, they are, by the nature of things, in crisis,'' Mr Bell said. ''Because smoking is so highly addictive, it imposes another crisis on them on top of the current health crisis they are going through.''

Fairfax has also obtained emails from mental health carers across Canberra, which show considerable concern at the smoking ban's potential to increase anxiety, stress and depression among those with mental health issues.

Details of the plan were revealed in June and fears similar to those of mental health carers were raised by Public Advocate Anita Phillips and the Human Rights Commission.

Chief Minister Katy Gallagher said in July that the issue was ''complicated'' and ordered more research into the problem.

There has been a period of consultation since then but it is unclear what, if any, changes have been made to the proposal during that time.

Canberra Action on Smoking and Health, an anti-smoking lobby group, are strong supporters of the smoking ban across ACT Health facilities.

President Alan Shroot said the Canberra Hospital had a ''disgraceful'' record on smoking and there was little consideration for others from smoking staff.

''We're very supportive of having a smoke-free facility - hospitals are places to promote health,'' Dr Shroot said. He said staff at the adult mental health unit should be doing everything they can to get patients to stop smoking cigarettes, including handing out nicotine patches.

''It's not fair to anyone,'' Dr Shroot said. ''Let's imagine there's someone who has got a bad chest, someone who is an asthmatic - is it fair that they're going to be exposed to the thousands of noxious chemicals in sidestream smoke because someone else is having problems?''

He said addictions should not be tolerated at any health site.

''What do you do if they're addicted to heroin or cocaine or marijuana? Some of these things will contribute towards their mental health [problems],'' Dr Shroot said.

''Just to leave it as an open place of addiction because people are addicted is really not acceptable.''