The pact, which will see Australia become the seventh nation to operate nuclear-powered submarines, will stress shipyards in Britain and the United States that are already beset by delays and cost overruns.

To help alleviate the strain, Australia will give Britain 2.4 billion pounds ($3.1 billion) toward design work on the conventionally armed SSN-AUKUS and expanding a Rolls-Royce RR.L plant that builds nuclear reactors for submarines.

Work is expected to start in the late 2020s, after at least A$2 billion worth of new shipbuilding facilities are completed.

Once the submarines are in the water, ASC will handle maintenance and logistics. The firm, which builds and maintains Australia's diesel-powered Collins-class fleet, will work with unspecified U.S. and British companies.

SSN-AUKUS submarines will also be built in Britain, and BAE won a 4 billion pound ($5.1 billion) contract in October 2023 to start design work and infrastructure at the shipyard at Barrow-in-Furness.

Nuclear submarines require a specialised workforce and BAE and ASC will set up a joint skills centre in South Australia to begin training workers.