The Commonwealth Government has revealed the cost for its Aukus nuclear-powered submarine deal with the United States and United Kingdom would be a staggering $368 billion.

Neither Defence nor the Government have confirmed Port Kembla is the preferred site but background leaks to media in San Diego indicate a strong preference for the Wollongong site.

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The Greens said the submarines would force deep cuts to expenditure on essential services, while making the city a nuclear target.

"Wollongong is a city with 100 years of peace activism," Wollongong Greens councillor Cath Blakey said.

"We have stood up to pig-headed prime ministers in the past, and we will do so again to say we want a peaceful city, that we say no to nuclearisation of our Port.

"I'm dismayed that the Labor government is leaking information about the preferred location of the nuclear submarine base. It shows not only how much they take the Illawarra for granted, but also outright contempt for our community.

"They're refusing to provide any information about how the floating nuclear power plants would be managed, overseen or their reactive waste managed."

Locating a base in the Illawarra would create thousands of ongoing jobs, advocates say.

NSW Ports says it has been kept in the dark about plans.

Greens Senator David Shoebridge blasted the Government for not being open with the population.

"This leaking of the Defence Department's preferred submarine base treats the people of the Illawarra like mugs," he said.

"Locating a nuclear submarine base in Port Kembla makes the Illawarra a potential target for nuclear attack, all with zero public consultation around the risks to the community.

"With this one decision, Labor is mortgaging our future in order to stoke regional tensions with a dangerous escalation in regional defence spending."