Scrapping state government funding earmarked for the mothballed Oakajee port project plus relocating a planned new stadium in Perth will help fund the Western Australian Labor party's $3.4 billion Metronet rail project.

The opposition believes it can save $250-300 million by building the stadium at Kitchener Park in the western suburb of Subiaco instead of at Burswood to the city's east, next to James Packer's Crown Casino.

WA Labor also wants to scrap $339 million that was put aside for the Oakajee port project in the state's Mid West region, which Japanese trading giant Mitsubishi indefinitely shelved in November.

The opposition's transport spokesman Ken Travers said Metronet would be paid for "by making the right decisions".

WA Labor leader Mark McGowan said $300 million would be saved by using a different location for the stadium, but Mr Travers put it at $250 million.

"We will deliver the same stadium in the same time frame and we will save $250 million to help fund Metronet," Mr Travers told an ABC Radio debate with Transport Minister Troy Buswell on Thursday.

"We will take the $339 million allocated to Oakajee, a project that is not happening, and put it into a project that will create jobs."