Opposition Leader Bill Shorten has committed $1 billion to the part-funding of WA Labor's Metronet rail project, if elected, while simultaneously pledging to cut all federal backing for the Barnett Government's Perth Freight Link (PFL).

Key points: Metronet will create jobs and ease congestion, Bill Shorten says

Metronet will create jobs and ease congestion, Bill Shorten says Metronet is key element of WA Labor's public transport policy

Metronet is key element of WA Labor's public transport policy If elected, Labor will cut federal support for Perth Freight Link

Mr Shorten made the announcement at a media conference with state Opposition Leader Mark McGowan in Perth, saying it would create jobs and ease congestion.

Last month he pledged to back Metronet if Labor won office, but he had not specified how much money his Government would provide for the fully-integrated rail network.

Labor now says it will contribute $760 million to the project by 2020, and a further $240 million over the following two years.

The funding would be contingent on Infrastructure Australia's approval.

Labor said it would "end the shambles that the Liberals have made of transport planning".

Metronet is the key element of WA Labor's public transport policy, which it will take to the 2017 state election.

Mr McGowan originally presented the Metronet plan at the last state election, when it was estimated to have a total cost of $5.2 billion.

Speaking alongside Mr Shorten on Monday, he said the project would now cost $2.5 billion.

Mr Shorten's federal funding would prioritise planning to build the Morley to Ellenbrook rail line, extend the northern suburbs line to Yanchep, extend the Armadale line to Byford, and start a circle line, linking the Mandurah line to the Thornlie line.

It would also go towards removing "unsafe level crossings that slow traffic" on the Midland, Armadale and Fremantle lines, and build a new station at Karnup on the Mandurah line.

PFL would lose support under Labor

The Barnett Government's plans for the PFL, which seeks to build a byway for heavy haulage from Perth's eastern industrial suburbs to Fremantle Port, would lose federal support under a Labor Government.

Labor has vowed to withdraw funding for the Perth Freight Link plan to extend Roe Highway. ( ABC News: Andrew O'Connor )

The Coalition has promised more than $1 billion towards the PFL, including towards the construction of a 3.3-kilometre tunnel.

But Labor described the project as "a road that goes part-way to a port that will be at full capacity within 10 years" and said a Shorten government would not proceed with the funding.

It is expected those funds would, at least in part, be diverted to Metronet.

A Shorten government would instead undertake "proper planning" for Perth's container capacity.

Labor would also continue with the $59 million upgrade to Leach Highway.

Ditching freight link 'reckless': Cormann

Federal Finance Minister Mathias Cormann condemned Labor's plan to cancel the Perth Freight Link to fund the Metronet project as "reckless", while WA Transport Minister Dean Nalder said the announcement lacked substance.

"There's no new funding here for Western Australia, it's just shifting priorities as far as they're concerned," Mr Nalder said.

Mr Nalder said Metronet would provide no transport solutions for Perth's northern corridor to Morley, which was the target of the Liberal's stalled MAX Light Rail project.

But he conceded if a federal Labor government removed the funding allocated to Perth Freight Link, it was unlikely the WA Government could foot the bill alone.

"I would say that without federal funding, we will find it difficult to fund it," he said.

Mr Cormann said the freight link was "a key foundation stone for our future economic success".

"We need the Perth Freight Link in order to get our goods to market more cheaply, more safely and to reduce congestion on key local arterial roads," he said.

"It is very reckless for Labor to propose to take that key piece of economic infrastructure away from Western Australia."