The opposition has flagged a cut in migration levels if it wins the next election, in a bid to tackle Australia's surge in population.
Opposition immigration spokesman Scott Morrison yesterday told The Australian the forecast of 36 million people by 2050 is unsustainable.
Mr Morrison says the Coalition would support skilled migrants coming, but was likely to cut other elements of the program, including family reunion.
"A net overseas migration intake of 300,000 (as occurred under the Rudd government) would not be a feature of future Coalition policy."
Mr Morrison said currently Australia is taking in a new migrant every 70 seconds, a growth rate higher than Canada, Britain and the US, and even India and China.
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Opposition Leader Tony Abbott last night backed Mr Morrison's comment that the prediction of a population of 35.9 million was not sustainable, saying the roads of Sydney and Melbourne were already choked.
But he stopped short of committing the Coalition to a cut in migration, saying decisions on the intake should be taken on a "year by year basis".
"Immigration has to be in Australia's national interest," he said on the ABC's Q&A program last night.
Mr Abbott last night backed the return of the temporary protection visa system and said a Coalition government would return asylum-seekers to their homelands if they no longer had a fear of persecution.
Population debate more than immigration: Burke
The debate on Australia's population is more than an "old style immigration debate", Population MinisterTony Burke said.
Over the next 12 months Mr Burke will develop a strategy to cope with a forecast 35.9 million people by 2050.
He told ABC Radio on Monday the plan was not just about tweaking immigration levels, but would examine all areas of government and how population could be better spread into the regions.
Immigration levels under the Rudd government had remained about the same as under the previous coalition government, so people should be "calm" about that part of the debate, he said.
"This is not simply an old style immigration debate," Mr Burke said.
"This is about people in the urban areas as well (those) who are seeing infrastructure pushed to capacity ... it's about some areas of the country where there are employers desperately need more people."
