Under the original deal inked in 2021, Australia was expected to receive at least two used and one new Virginia-class submarines, public outlet the Australian Broadcasting Corporation reported.
Marles, however, told reporters that under the revised deal, Australia will now purchase only second-hand Virginia-class submarines from the US.
The joint US-UK-Australia statement described the change as a mutual streamlining "simplifying supply-chain management, operational and maintenance requirements, and maximizing cost efficiencies."
The project under the AUKUS alliance, among the US, UK, and Australia, is seen as crucial to enhancing defense capabilities.
For the project, the UK had pledged £4 billion ($5.3 billion), the US $17.5 billion, and Australia more than 30 billion Australian dollars ($20.7 billion).