The call comes amid concerns about parking and the provisional layout of the hospital causing hardship to patients with limited mobility and mental health problems.

Australian Nursing and Midwifery Federation ACT secretary Jenny Miragaya said the current plan was a "significant departure" from the government's initial 2011 proposal.

In a letter to Deputy Director-General of Health Infrastructure Paul Carmody, Ms Miragaya said she was concerned the hospital had reneged on a promise of 140 sub-acute care beds and feared "they would simply provide a reconfiguration of services".

"[We] therefore seek urgent clarification in respect of this glaring discrepancy in respect of the ACT government commitment made in 2011, and what is now proposed in 2015," she said.

But a spokesman for ACT Health Minister Simon Corbell said the reference design for the hospital also included 75 additional day spaces, in addition to the 140 overnight beds.

"The proposed bed numbers reflect the model of care and the specific services that will be provided in the new facility," he said.

"Planning to date identifies that the University of Canberra public hospital will meet current and projected demand to 2025."

Construction on the new hospital, which is expected to cost more than $100 million and alleviate stress on Canberra and Calvary hospitals, will begin early year.

The hospital, which will be built on the corner of Aikman Drive and Ginninderra Drive, will feature sensory areas for dementia patients and offer a dedicated aged care assessment team and residential aged care specialist.

Last month, Mr Corbell unveiled a first glimpse of the planned hospital which will provide a range of rehabilitation services and treat mental health conditions as well as providing targeted services and care for older Canberrans.

But Ms Miragaya questioned whether the planned design was appropriate for "a building providing clinical patient and rehabilitation services necessitating significant distances to be travelled by consumers who may be mobility impaired".

She said the initial concept plan for the hospital was a single-story facility although this was later revised to be two stories with the ACT government still considering feedback.

"The ANMF remains concerned … that the physical size of the facility may have a potential deleterious impact on the amenity of the site in terms of services by consumers who are likely to be physically impaired, especially in terms of mobility," she said.

Mr Corbell's spokesman said the two-story reference design was based on the input of key stakeholders including staff and consumer representatives.

Ms Miragaya said confusion about parking options and the possibility of paid parking needed to be addressed by the ACT government.

"Given the very emotive responses parking issues engender within the ACT community, particularly where access to health care services are concerned, this matter needs to be clarified as a matter of urgency," she said.

A spokesman for Mr Corbell said provisions for visitor and patient parking were a key consideration in the planning of the hospital.

"Details regarding parking are in the process of being finalised, and as such information on parking was not included in the reference design.

"Any parking on the site of UCPH will be finalised during the development application process."

Ms Miragaya said ACT Health had already considered feedback and would provide additional disabled parks and extend a covered way so patients would not be dropped off in the rain.

"That may be fine in any other facility but this one is built specifically for the elderly and those with disabilities and mental health problems," she said.

"If you have to drop your elderly father with dementia off and then leave him to find a park elsewhere in the university, what do you think will happen to him?"

A final design for the new sub-acute hospital is expected towards the end of this year.