Dick Smith is launching an advertising campaign against ABC TV news and current affairs, which he says has warped the debate he has tried to spur over Australian population growth.

He claims both Labor and Liberal politicians have told him they agree that Australia needs to cut its immigration intake to avoid future social and environmental fracturing, but they say they cannot say so publicly because the ABC will label them racist.

"This is warping our democratic process, it is basically treasonous," the businessman and publisher told Fairfax Media.

He claims ABC television's news and current affairs has deliberately ignored his campaign over the issue. In recent weeks Mr Smith has spent $1 million in advertising promoting his campaign to have Australia adopt a policy that would slash immigration numbers to around 70,000 - around the levels of the Hawke and Keating era - in order to see population level off at around 30,000,000.