Marshall’s concept also appears likely to delay – or even kill off – hopes for a broader contemporary art gallery for the site, which is currently the subject of an international design competition.

He said today the absence of a national indigenous gallery was a “significant omission by Australian governments and a fantastic opportunity for South Australia”.

However, the Northern Territory Government has already announced a $50 million plan to build what it calls an “iconic National Aboriginal Art Gallery” in Alice Springs, which would be linked to a sister National Aboriginal Cultural Centre.

The plans are well-advanced after the establishment of a high-profile steering committee and months of consultation with the Alice Springs community to determine the best location for the institution. Chief Minister Michael Gunner prefers a location at Anzac Hill in the outback town, as part of broader plans to rejuvenate Alice Springs.

It’s unclear how Marshall’s concept would fit with Adelaide Contemporary – Art Gallery of South Australia director Nick Mitzevich’s plan for an internationally significant new gallery and sculpture park for the old RAH site.

Adelaide Contemporary is part of Labor’s vision for the old RAH site, depending on the results of the international design competition.

And there is a connection between the Adelaide Contemporary proposal and the Territory plans.

The steering committee for the Northern Territory proposal includes experienced arts administrator Michael Lynch, who is also heading the design jury for Adelaide Contemporary.

The design competition jury is due to make its final recommendation in the middle of this year, after which Labor said it would make a decision about funding the gallery.

Under Mitzevich’s concept, the new gallery would have three streams: room to display, for the first time, the gallery’s entire 42,000-piece collection of works; a “gallery of time” which would display Aboriginal, Asian and European works of art alongside each other in chronological order; and a gallery of 21st-century art.

Mitzevich didn’t want to buy into election debate today and would not comment when contacted by InDaily.

Premier Jay Weatherill said that while he welcomed aspects of the Liberals’ plan, Marshall’s “opposition” to the tram extension to Norwood would undermine the gallery concept.

A new tram extension in the city is almost complete, with its terminating point outside the old RAH site. Labor announced this week that it would extend the tram line through Kent Town to the Parade – a plan that received an unenthusiastic response from Marshall.

“I welcome the Liberals’ bipartisan support for a plan which is similar to the Adelaide Contemporary project, including our proposed sculpture park,” Weatherill said in a statement.

“Nick Mitzevich’s vision for a new gallery on the site includes a contemporary indigenous art gallery.

“Sadly, the Liberals’ plan is undermined by Steven Marshall’s short-sightedness in opposing a tram extension to The Parade.”

In response to questions from InDaily, Marshall insisted his plan would be larger in scope and more significant than the Northern Territory proposal.

He also claimed Adelaide was a better location for the institution than Alice Springs.

“Adelaide is the most suitable location for a national gallery which recognises the unique art and culture of our First People,” he said.

“The proposal for Alice Springs is a much smaller gallery for art only. Our proposal recognises that South Australia has the world’s most significant collection of Aboriginal culture but current space allows only 5 per cent of it to be seen by the public while much of the rest of the collection is stored in conditions that put some of it at risk.”

He said the estimated total cost of the gallery would be between $200 million and $250 million – “similar to the Weatherill Government’s indicative cost of $250 million for its contemporary art gallery”.

“Construction would begin as soon as possible after the site remediation work is completed. Labor has known since 2007 that new uses for this prime site would be needed but since then has botched the planning and failed to deliver the coherent vision this site deserves.”

Marshall did not answer InDaily’s question asked about how the gallery would be managed, including the role of the Tandanya National Aboriginal Cultural Institute, located just a few streets away from the old RAH site.

InDaily has asked the Northern Territory Government for its response.