Australia announced on Monday it would buy up to five US submarines in an ambitious effort to bulk up Western muscle in the face of a rising China.

With the help of the United States and Britain, Australia will also embark upon a 30-year plan to build its own fleet of nuclear-powered subs.

Australian Prime Minister Anthony Albanese said the deal was the country's biggest-ever military upgrade, while US President Joe Biden said it would ensure the region remained "free and open".

But former prime minister Paul Keating has derided it as a "great misadventure".

"History will be the judge of this project in the end, but I want my name clearly recorded among those who say it is a great mistake," he said in a statement.

The former Labor prime minister -- who led the country between 1991 and 1996 -- said Australia had blindly followed the United States and Britain, and that China posed no tangible military threat.

"What would be the point of China wanting to occupy Sydney and Melbourne? Militarily? And could they ever do it," he said.

"The question is so dumb, it's hardly worth an answer."

Keating said Australia was beginning a "dangerous and unnecessary journey" at the urging of the United States, and that this could carry "deadly consequences" if the country became tangled in future conflicts.

"Signing the country up to the foreign proclivities of another country -- the United States -- with the gormless Brits lunging along behind is not a pretty sight," he said.

Acquiring submarines powered by nuclear reactors puts Australia in an elite club and at the forefront of US-led efforts to push back against Chinese military expansion.

While Australia has ruled out deploying atomic weapons, its submarine plan marks a significant new stage in the confrontation with China, which has been racing to strengthen its own sophisticated naval fleet.