MELBOURNE, Australia — Some members of Australia’s governing Liberal Party want voters to believe immigrants are bad for the economy, draining resources and causing wages to stagnate. But a newly published report, written by the same conservative government, reveals the opposite — immigration is a critical engine of the country’s growth.

The report, first published on Tuesday by Fairfax Media after journalists submitted multiple Freedom of Information requests, concluded that reducing immigration would cost the national budget billions of dollars and reduce job growth.

One of every two Australians is an immigrant, or the child of an immigrant. About a quarter of Australia’s population is foreign born, roughly twice the rate of the United States.

But immigration is a hotly contested issue, especially as Australia’s cities have been growing rapidly without the infrastructure to match, and the far-right contingent of the Liberal Party has been pushing to reduce immigration levels by tens of thousands of immigrants per year.