Make ship order now, Andrews tells PM

New Defence ship-building orders for Melbourne are welcome but they need to be made immediately, Premier Daniel Andrews says.

Prime Minister Tony Abbott is set to announce $20 billion worth of ship building contracts for South Australia and Victoria, The Australian newspaper reports.

"A continuous build program is very important. But if it takes two years to get going, then I fear we won't have a ship-building sector in our state," Mr Andrews told reporters on Monday.

Victoria and South Australia have pushed the federal government for Defence orders to be placed to keep manufacturing jobs in both states.

Mr Andrews said without an immediate order for new patrol boats, the potential $20 billion frigate-building order could come too late.

"I fear that companies like BAE and the Williamstown shipyards and the integrated supply chain that feed into that firm simply won't be there - they will die, they will go," he said.