Questions over Australia's submarine plan

AUSTRALIA'S ATTACK CLASS SUBMARINE PROGRAM

* 12 submarines are being designed and built to replace the ageing Collins class subs at a cost of $50 billion

* Preliminary design phase is under way with Naval Group's team in France/Adelaide and Lockheed-Martin Australia's team in Adelaide

* 137 Australian companies and organisations currently have sub-contracts

* The build of a hull qualification section in Adelaide due to start in 2023 will certify the Australian workers and construction yard equipment ahead of the construction of the first submarine

* More sub-contractors will be sought ranging from hydraulic systems to galley equipment suppliers

* Non-government parties are concerned there won't be enough Australian jobs generated from the program

* There are also questions still to be resolved as to whether Western Australia will benefit from any of the work

* The first submarine is due to be delivered to the Royal Australian Navy in 2032.