Two separate construction projects, one in Australia and another in South Africa, have made claims to become the tallest building in the southern hemisphere.

The projects, which are proposals at present, have received provisional backing from their respective government authorities.

The city of Melbourne in the State of Victoria, Australia hopes to build a 388m (1,272 ft) tower rising 108 stories, while the South African project - to be constructed in Centurion just south of Pretoria in Gauteng Province - includes ambitious plans for three towers, the tallest of which will reach 447m (1,466 ft) and have 110 stories.

To be named Australia 108, the Melbourne building will cost in the region of A$600m (£364m, €430m, US$572m) and will feature a 288-room hotel, 646 apartments as well as retail and office space.

Australian architecture firm, Fender Katsalidis designed the building and were also responsible for another iconic Melbourne skyscraper - and currently the city's tallest building - Eureka Tower. Architect Nonda Katsalidis said he used the Commonwealth star on the Australian flag as inspiration for the design of the building.

The hotel will occupy 18 levels of the building and its facilities will be accessible to residents of the building and public at large. The hotel will have a separate lobby entrance and lift access, away from the residents' entry.

A double storey Sky Lobby on level 83 will feature two restaurants, two bars and lounge areas. These areas will jut out of the building and be located in the starburst points that crown the building. The hotel and swimming pool, gym and spa will be located on level 84. Another feature of the building will be the glass enclosed Star Bar to be located on level 108, allowing dramatic views of Melbourne.

By comparison the South African project, to be called Centurion Symbio-City, will consist of two office buildings and one residential tower, which will also include hotel and retail facilities. It is estimated the project will cost around ZAR18bn (£1,14bn, US$1,8bn, €1,35bn).

One of the companies promoting the project, Cresco Properties, says the hotel's reception area will be located on the 80th floor. The hotel will consist of 295 rooms - 120 business traveller rooms, 80 superior rooms, 60 upscale deluxe rooms and 35 master suites. There will also be 85 managed two and three bedroom penthouse apartments. A pool deck with infinity edge pool and health hydro form part of the facilities.

The project also incorporates a conference facility for 300 delegates, a food court and four other restaurants.

According to the City of Tshwane (the metropole incorporating greater Pretoria), the development will be built on and around Centurion Lake on 10 hectares (24,7 acres) of land. The project has easy transport links to the N1 motorway and Gautrain Centurion Station. It was designed by Johannesburg architectural firm, @126 Architects.

The Australian project has indicated a completion year of 2018, while the South African development is looking at 2020/2022.