The billionaire on Monday revealed details of what he said could become one of the world's largest steel production facilities, with the necessary infrastructure to double production over time.

The project will use state‐of‐the‐art technologies and focus on producing semi‐finished steel for strategic and growing markets around the world.

“Using the most advanced technologies and our own local resources, we will aim to be one of the most competitive steel producers globally," Mr Gupta said.

“Thousands of job opportunities will be created throughout the construction phase and from the plant’s ongoing operations.

“This will see a new generation of steelmakers proudly competing on the world stage, and reflects our desire to transform Whyalla into both an Australian and global powerhouse of industry for generations to come.”

Mr Gupta also outlined a $600 million expansion of Whyalla's existing steel mill to lift annual production to 1.8 million tonnes.

Contracts have been signed to develop a rail and structural heavy section mill and for a pulverised coal injection plant allowing the Whyalla operations to cut costs, introduce new products and be more environmentally sustainable.

Mr Gupta was joined on Monday by Prime Minister Scott Morrison, Opposition Leader Bill Shorten and SA Premier Steven Marshall.

He said when he first came to the city his briefing notes suggested a rescue of the steel operations was not possible.

"This was the poor cousin, a broken steel town," he said.

"But those of you who know me that's like red rag to a bull."

Mr Gupta said what he found was a "diamond" and a company with a workforce that was willing to fight.

Mr Morrison described Whyalla as the comeback city of Australia with a bright future in investment and jobs.

"This is the turnaround state and this is the comeback city in Australia when we're talking about Whyalla," the PM said.

While Mr Marshall said there was a growing confidence that Whyalla's best days for manufacturing lay ahead.

"Whyalla will once against be a powerhouse of industrial activity," he said.

On a day of what local authorities described as "transformational announcements", the city council said other new projects would include a $45 million hotel, a $145 million horticulture facility and a $6 million organic recycling business.

It's been suggested the expansion of steel production and the other developments will boost Whyalla's population from about 20,000 to about 80,000.

Australian Associated Press