An ambitious plan to build Australia's tallest tower in the inner city suburb of Southbank has sparked fears that Melbourne could be transformed into an "Asian mega city".

Key points: Developers revealed designs for a $2 billion skyscraper, complete with school and car dealership

Developers revealed designs for a $2 billion skyscraper, complete with school and car dealership The building would be 356m, making it the highest in Australia, but planning applications have not been lodged

The building would be 356m, making it the highest in Australia, but planning applications have not been lodged Urban planning experts have warned Melbourne is at risk of becoming a high-rise 'mega city'

But opinion is divided on whether the $2 billion project will even go ahead, with one planning expert predicting that it's nothing more than a stunt designed to build the profile of the developers and architects.

On Wednesday, property developers Beulah International announced they had selected a design for its site in Southbank, near Freshwater Place.

The blueprint was pulled together by the Dutch firm UNStudio and Melbourne's Cox Architecture, and would see a 356-metre tower built in the inner city.

The Green Spine building would have a botanic garden, a cinema, library and school. ( Supplied )

The structure, which is yet to get approval, would include a school, library, cinema, car dealership and botanic garden.

Next to it would be a 252 metre building with offices, restaurants and a hotel.

High-density a 'doomed model'

But the proposal has caused serious concern in urban planning circles, with one expert warning that Melbourne's flirtation with higher-density living was a misstep.

"This is a doomed model … and we can see the impacts of this by just going to cities that have remade themselves in this image and they're not great places to live," said Michael Buxton, a planning expert from the School of Global, Urban and Social Studies at RMIT University.

"What we're doing now is building a city where we're separating people from each other and the street," he said.

"There are no community activities and these are places that are very difficult to live in."

He is worried that Melbourne will lose its high-heritage value if it continues to pursues density over liveability, and believes the focus should instead be on mimicking cities in northern Europe and Scandinavia.

"All those European cities that our politicians generally can't wait to get to every time they go on their holidays," Professor Buxton said.

"They know that these cities are the places to be, but they're turning Melbourne into an increasingly difficult to live in city because they can't resist the lure of the development model and the big development dollar.

"We're turning Melbourne from a city with very high heritage value into a high-rise model of a city based on … an Asian mega city."

'It's a way of getting your name about'

But some experts, like David Nichols from the University of Melbourne, are unconvinced the project will even get off the ground.

He said the buildings were beautifully designed.

"But whether it will ever be built, I'm very, very sceptical frankly," Dr Nichols said.

Planning experts said skyscrapers detach residents from the street and the community. ( Supplied )

He believed it was just a profile-building exercise.

"It's a way of getting your name about, it's a way of becoming known and being seen and people can see you can do great things," he said.

"My guess is if this was passed through and they were allowed to build it as is, they'd be very surprised.

"They'd be pleased, I'm sure. and I'm not saying for a second that they couldn't do it if they were given the license to but I think that it's very unlikely that it would come through in the kind of form that we see in these beautiful pictures."

Dr Nichols said residents living in high-rise buildings were often cut-off from the community.

"If it comes to the crunch and you do want some access to some community, then it's going to be hard to find," he said.

No planning application lodged

At the moment, the building's soaring height is expected to breach the air safety limit set by the Civil Aviation Safety Authority.

It would also be prohibited by the City of Melbourne's current planning laws, according to Greens councillor Rohan Leppert.

"It's being presented as a sure thing because there's a pretty remarkable and powerful PR campaign," Cr Leppert said.

"The only way it would be able to be approved is if the rules of the planning scheme were altered just for this site, and that's where this gets really, really murky," he said.

"We've seen a lot of decisions recently where that happened, Crown Tower at 1 Queensbridge or the Apple Store at Federation Square.

"Every time government reaches in and says, 'Let's change the rules for the richest players in town', public faith in the planning system gets eroded."

A spokeswoman for the Planning Minister, Richard Wynne, said there was no application before the department for the development.

"At present this proposal is purely speculative," she said.

"Any proposal to breach the air safety height limit would be referred to the Civil Aviation Safety Authority."