The Department of Defence says Newcastle, Port Kembla and Brisbane best fit the criteria for a new $10 billion nuclear submarine base and will be the only ports considered in a feasibility study.
Prime Minister Scott Morrison has been accused of politicising the key national security decision after announcing last month that one of the three cities would host the base.
Past Defence reports have ranked the three ports lowly on a short-list of preferred locations, instead favouring four sites in Sydney and two locations in Jervis Bay. Newcastle was ranked seventh.
"In considering options for a future east coast naval base, all feasible east coast ports were considered," a Defence spokesperson said on Thursday.
"The three locations that best matched the assessment criteria for a submarine base were Port Kembla and the ports of Newcastle and Brisbane. These locations will be the only ones further considered for feasibility as an east coast naval base."
Defence assistant secretary Dan Fankhauser told senates estimates this month that the three sites had been "assessed against a range of basing criteria which included access to exercise-operating areas and being close to industrial infrastructure and close to significant population centres to support personnel and recruitment".
An Australian Financial Review report on Wednesday said Newcastle had emerged as the frontrunner to host an east coast base, ahead of Port Kembla and Brisbane.
The report quoted sources as saying the government was considering whether it would have to buy out the Chinese half-stake in the Port of Newcastle if it wanted the base in the Hunter.
Defence has started talking to the NSW and Queensland governments about the three base options, but the Newcastle Herald has been told the department has not undertaken preparatory work to buy back any element of Newcastle's port.
Defence deputy secretary Celia Perkins told the senate estimates hearing that the $10 billion Mr Morrison flagged in last month's budget for submarine infrastructure would be spent "primarily" on the new base.
She said the feasibility study would be completed by the "latter half of 2023".
