Prime Minister Scott Morrison has dismissed Labor's plan to create a strategic shipping fleet, arguing lifting the number of Australian-flagged vessels serves union demands.

The federal opposition has announced a plan to establish the fleet, which is likely to include up to a dozen vessels including oil tankers, container ships and gas carriers.

The Australian-flagged and crewed vessels will be privately owned and operate on a commercial basis, but could be requisitioned by the government in times of need.

Mr Morrison said Labor had not committed to properly building Australia's Navy, failing to commission one ship when they were last in government.

"They seem to be more interested in doing what the MUA tells them to do, the maritime union, than what the Australian people want them to do," he told reporters in Hobart on Sunday.

He said the coalition had undertaken the biggest naval shipbuilding program since the Second World War.

"That is the scale of our commitment when it comes to our naval shipbuilding program," the prime minister said.

Labor has warned Australia's merchant fleet is disappearing, despite relying on shipping to move 99 per cent of imports and exports.

The number of Australian-flagged vessels has shrunk from 100 to 14 over the past 30 years.

Opposition Leader Bill Shorten and transport spokesman Anthony Albanese said the decline had destroyed the jobs of seafarers and created a situation where essential fuel supply vessels were not crewed by Australians.

"The existence of a vibrant Australian shipping industry serves the nation's economic, environmental and national security interests," they said in a statement.

An elected Labor government would first appoint a task force to guide the establishment of a fleet.

Labor has also pledged to re-establish the scrapped Maritime Workforce Development forum and enforce existing laws around coastal shipping.