A block and a-half of central Dunedin - including part of the Cadbury factory and stretching across St Andrew St - is believed to be the frontrunner to be named as the site for the new $1.4 billion Dunedin Hospital later today.

A formal announcement is scheduled for 11am, but the Otago Daily Times understands the western side of the Cadbury site, together with the block bordered by Hanover, Castle, Cumberland and St Andrew Sts, is the preferred site.

The main hospital building is likely to be one of the tallest buildings in Dunedin.

The plot includes land occupied by the former Cadbury factory, Work and Income, Vehicle Testing NZ and a cluster of other businesses, as well as a University of Otago hall of residence.

Cadbury ceased making chocolate at its Cumberland St site in March, although the Cadbury World tourist attraction remains open, and consent has been issued for it to move to the other side of the Cadbury site.

The remaining land was meant to have gone on the market earlier this year, but the site has not yet listed by CBRE, the firm Cadbury owner Mondelez International said would handle the sale.

The site matches the requirements set out by Southern Partnership Group chairman Pete Hodgson, that it be a flat site south of the university and north of the Octagon.

In December, Mr Hodgson ruled out the existing hospital site, and said the university's Cumberland and Hayward hostels would be retained - suggesting the hospital would not be built on the block of land across Cumberland St from the hospital.

In addition, Mr Hodgson said he did not think the DHB's Fraser Building, next to Cumberland College, would be part of the new hospital.

Mr Hodgson has also suggested the hospital was likely to be built on multiple parcels of land rather than a single site.

Other possible locations between the Octagon and the university have multiple commercial tenants.

By comparison the new site includes buildings already owned by the Crown as well as the recently vacated Cadbury land, and probably entails the least amount of land purchases or possible acquisitions under the Public Works Act.

One potential stumbling block is the recently opened Te Rangi Hiroa residential college, but the 2014 building would be a fitting addition to the hospital, being named after Sir Peter Buck, the first Maori medical graduate of a New Zealand university.

Other prominent buildings on the site are Work and Income's premises, Midas and Beaurepaires, and there is also a sizeable vacant lot used for parking.

Helpfully, there is a through road running between Warehouse Stationary and Lighting Direct - a similar drive also exists across the Cadbury site.

Mr Hodgson has stressed a new hospital needs to be near the Medical School, which is in Great King St, and the site meets that requirement.

It is also diagonally across the road from oncology - the only major hospital building expected to be retained.

The site is bounded on either side by State Highway 1 but is wide, which should help reduce traffic disruption during construction.

The ODT understands there may be some roading changes to accommodate the new hospital.

The Dunedin Energy Centre is also nearby, and the Local Advisory Group - set up by Mr Hodgson to assist the rebuild project - is known to have been studying creating a renewable energy scheme to power the hospital, university and nearby businesses.

Property owners on the block bordered by Hanover, Castle, Cumberland and St Andrew Sts told the Otago Daily Times they had not been approached about the use of their land for the new hospital.

Aurora Energy runs a substation on the site.

When asked whether it had been approached about the use of its land, head of external relations Gary Johnson referred all questions to the Southern Partnership Group.

Visit www.odt.co.nz after 11am today for more details on the site of the new Dunedin Hospital.