FOUR in 10 Australians believe Australia's projected population of 35 million by 2049 will be too many people, according to an Age/Nielsen poll.

As Prime Minister Kevin Rudd talks up the idea of a ''big Australia'', the public is more dubious about the expansion. Australia's population recently passed 22 million due to near-record levels of net migration and the highest birthrate since the 1970s.

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Only 30 per cent think 35 million would be about right; 26 per cent have no opinion, while 2 per cent say it would be too few people.

People are evenly split, on 43 per cent each, between those who say present immigration is too high or about right. Just 9 per cent said immigration is too low. The numbers are little changed from 2001.