Defence Minister Marise Payne has rubbished Tony Abbott's call for Australia to acquire nuclear-powered submarines, saying they would be too expensive and the country lacks the know-how to sustain them.
In his second major speech of the week, the former prime minister has made the case for a plan B to the government's decision to award a $50 billion new-fleet contract to French shipbuilder DCNS.
"Not more robustly challenging the nuclear no-go mindset is probably the biggest regret I have from my time as PM," Mr Abbott told the Centre for Independent Studies in Sydney on Thursday.
Senator Payne said Australia lacked the qualified personnel, experience, infrastructure, training facilities and regulatory systems required to design, construct, operate and maintain a fleet of nuclear-powered submarines.
"Developing this capability domestically would take far longer than a decade," she told AAP.
"The advantages of acquiring nuclear-powered submarines would be lost without the capacity to sustain them in Australia, particularly if we were required to support the submarines in Hawaii or Guam noting time required to reach and return from these locations for maintenance."
She said nuclear submarines would come at a "very substantial cost premium".
Mr Abbott said Australia in a decade or so might face a security crisis in our region with inadequate means to fight back.
He recalled being told Australia's two Collins class submarines were unable to shadow a Russian naval task force when it appeared north of the country during the Brisbane G20 in 2014.
"They simply couldn't get there in time," he said of their underwater cruising speed of just 10 knots.
Mr Abbott praised the Turnbull government for seeing through the process he set up to choose the next submarine build.
But he questioned whether the best of the bids was chosen, given the absolute soonest the first submarine could be received was the early 2030s.
"We don't build our jet fighters here, for instance, so why insist on a local build especially if there's a big cost penalty?"
Mr Abbott said the government should at least consider the option of nuclear-powered submarines.
"There is still a chance for further thought on this; there may even be a duty to consider plan B should the design process be further delayed or should regional tensions show little sign of abating," he said.
He stressed he did not want to interrupt the process underway given it had languished for so long but a parallel discussion should be had on nuclear.
Nuclear-powered subs could stay submerged as long as the crew could endure, never have to refuel and could travel at nearly 40 knots, Mr Abbott said.
