Acting Prime Minister Richard Marles, who is also the defence minister, would not be drawn on confirming key details of the highly anticipated AUKUS announcement by Anthony Albanese in the US next week.

Speculation is mounting following leaks from the US and UK that Australia will acquire five Virginia-class submarines, with the remaining boats to combine a British design with US technology.

“This is the biggest step forward in our military capability that we’ve had since the end of the Second World War,” he told Nine on Friday.

“And this more than anything that we can do, will allow us in a pretty difficult world to look after ourselves.”

Asked about the potential for a capability gap until the delivery of the nuclear-powered submarines, Marles backed the current Collins-class fleet, but said a more potent boat was needed in the next decade.

“There is nothing which gives any adversary a second thought more than a capable submarine, which is why it’s so important that we’re bringing to bear this capability in the future,” he said.

Opposition Leader Peter Dutton said the impending announcement was “a great outcome for the country”.

“The Virginia-class is an established class, so you don’t have the problems of a first-in-type, the new design, cost blowouts,” he said.

“The acquisition of the Virginia-class is in our country’s best interests and we strongly support it.”

Meanwhile, China’s foreign ministry urged Australia, the UK, and US to “abandon the Cold War mentality and zero-sum games”.