Two regional NSW ports have emerged as preferred options for a possible submarine base on Australia's east coast amid reports Sydney Harbour was being considered for the new naval home.
The NSW government on Wednesday floated both Port Kembla and Newcastle as potential sites.
"We know there are a number of viable options for a new submarine base, including Newcastle and Port Kembla, and these are under consideration by the Navy," a spokeswoman for NSW Trade and Industry Minister Niall Blair said.
"The NSW government strongly supports substantial future industry opportunities, such as an expanded naval presence in NSW, and in ports such as Newcastle and Port Kembla."
It followed reports that Sydney Harbour was being considered as the best option for a new fleet of subs.
"Sydney Harbour provides the best three currently available options for a sustainable east coast home port," a Defence Department study obtained by Fairfax Media and published on Wednesday says.
The study refers to a "two ocean policy", under which some of the new fleet of 12 Hunter Class boats could be based at Fleet Base East at Garden Island, HMAS Waterhen at Balls Head Bay or Cockatoo Island and others at the submarine base in Fremantle, Western Australia.
Mr Blair's spokeswoman said the NSW government understood the navy had been conducting comprehensive studies but it was "too early to speculate on what the final decisions might be".
Defence Minister Marise Payne said the first vessel was not expected to enter service until the early 2030s.
"A range of initial submarine basing options are expected to be presented by Defence to government for consideration in late 2019," Ms Payne told AAP in a statement.
