The multibillion-dollar Melbourne Metro rail project will boost the Australian economy, the nation's top infrastructure advisers have declared, placing pressure on the Turnbull government to increase funding to Victorian major projects.

The business case for the $10.9 billion project to build twin nine-kilometre rail tunnels under the city, linking Kensington to South Yarra, has been assessed by Infrastructure Australia and has been placed among the highest priority projects for the nation category.

"Overall, Infrastructure Australia is confident that the benefits of the project will exceed its costs and that the proposed solution will provide a net benefit to the Australian economy," the body's project evaluation says.

The approval by the nation's independent infrastructure adviser has restarted calls from Victoria for Canberra to contribute more taxpayers' dollars to projects in the state.