The Greens have warned Australia acquiring nuclear-powered submarines will create "floating Chernobyls" in the heart of major cities.
The UK and US will give Australia access to top secret nuclear propulsion technology for a fleet of new submarines to be built in Adelaide through new security pact AUKUS.
Greens leader Adam Bandt believes the move increases the prospect of nuclear war in the region and puts Australia in the firing line.
"It's a dangerous decision that will make Australia less safe by putting floating Chernobyls in the heart of our major cities," he told the ABC on Thursday.
"It's a terrible decision. It's one of the worst security decisions in decades."
The submarines will not require a civilian nuclear capability, but rather have reactors and fuel which will last the life of the vessel.
Former Labor prime minister Paul Keating said the arrangement would result in a dramatic loss of Australian sovereignty and choice over whether to engage in conflict.
Mr Keating said the decision had been made at a time when US reliability in military engagements was under question.
"If the United States military with all its might could not beat a bunch of Taliban rebels with AK47 rifles in pickup trucks, what chance would it have in a full blown war against China, not only the biggest state in the world but the commander and occupant of the largest land mass in Asia?" he said.
"When it comes to conflict, particularly among great powers, land beats water every time."
The government has sunk $2.4 billion on the French program and is negotiating on other compensation, which remains commercial in confidence.
Opposition Leader Anthony Albanese signalled Labor would support the new submarines but criticised the waste of scrapping the $90 billion French deal.
Mr Albanese said the program spanned eight years, three prime ministers, six defence ministers and billions of dollars.
"This is the most expensive example of something that has characterised this government: its ability to promise but its inability to deliver," he told reporters.
Independent senator and former submariner Rex Patrick wants an urgent parliamentary inquiry to report before the next federal election.
Senator Patrick, who has been a vocal critic of the French deal, said scrutiny was crucial.
"We have to be careful we don't move from one massive procurement disaster into something else that hasn't been thought through properly," he said.
Australian Associated Press