Subs deal isn't economic saviour: Greens

Building 12 subs in South Australian is good for the state but can't be the only driver of its struggling economy, Greens leader Richard Di Natale says.

A deal to build 12 submarines in South Australia is good news but can't be relied on to save the state's struggling economy, according to the Greens.

Federal party leader Richard Di Natale says South Australia's capacity to build the submarines is evident but the state shouldn't put all its eggs in one basket.

Speaking in Melbourne, Senator Di Natale said it wasn't the only pathway for economic prosperity and the big challenge was to diversify South Australia's industry.

"We can't rely entirely on this contract to get South Australia out of its economic woes," the Greens leader told reporters.

Prime Minister Malcolm Turnbull announced on Tuesday a French company, backed by the French government, had been awarded the contract to build the submarine fleet, with the ships to be built in Adelaide securing 2800 jobs.