Former prime minister Paul Keating has fired a fresh torpedo at the AUKUS deal, claiming Defence Minister Richard Marles has changed his argument to justify the submarine purchases.

Mr Keating, who has already been publicly critical of the $368 billion deal, said in an opinion article the government had shifted the need for the vessels from protecting the country from invasion, to instead needing to protect sea lanes for trade.

“In one week the government has gone from needing outrageously expensive nuclear submarines to weigh off a potential invasive threat from China to now – hold it – needing them, principally, to protect our sea lanes, an altogether different issue as to scale, purpose and urgency,” he wrote in the Australian Financial Review on Friday.

“Marles has been pushed out to argue not against any supposed invasion by China, but rather, secondarily, the protection of sea lanes – the very same sea lanes that service and fuel China’s massive material demands.”

Mr Marles hit back, saying the government had not changed any view surrounding the submarine deal.

“We deeply respect Paul Keating and his opinion is one that should be expressed, but we’ve been really clear about the fact that in 2023 we’ve got changed circumstances,” he told Nine’s Today program on Friday.

“We have a country today which is much more connected in terms of trade with the world than we ever have been before, certainly than we were in the 1990, and we face the situation that the old capability … which is a conventional submarine, is going to become less capable in the 2030s.”

Nationals leader David Littleproud also rejected Mr Keating’s latest criticism, saying the former prime minister was living in the past.

“We’re disappointed with Paul Keating’s comments – he’s living in a 1990s utopia that doesn’t exist any more,” he said.

“Unfortunately, I think he’s channelling the anger of some of Richard’s backbench that’s going to tear this mob apart and this is why this is holding us back on talking sensibly about a civil nuclear energy system in Australia.”

The comments from Mr Keating follow his appearance at the National Press Club last week, where he hit out at AUKUS, labelling it the “worst deal in all history”.

– AAP