A call to lift Australia's population to 50 million by 2050 has met strong resistance from politicians and environmentalists. About 500 delegates convened in Melbourne this week for Australia's first national population summit. Many of the speakers - among them politicians, economists, and businessmen - called for a dramatic rise in Australia's population over the next 50 years, from 19 million today to 50 million in 2050. They argue that failure to increase the number of immigrants would doom the country to lagging behind its competitors in the 21st century. Billionaire industrial magnate Dick Pratt, the nation's third richest man, said that Canada, with a population 1.5 times that of Australia, was gaining a vital edge in the race for skilled workers and a more innovative economy because it planned to accept 225,000 migrants this year - almost triple the number that Canberra planned to take. Australia's migrant intake is expected to be about 85,000. Leader of the opposition Labor Party Simon Crean said Australia needed a population growth target and that a 'do nothing' approach would result in an ageing and declining society. Former prime ministers Bob Hawke and Malcolm Fraser also put themselves firmly in the camp of higher immigration. Many Australians are worried that falling birth rates mean that in future there will be fewer people of working age who will be expected to look after a growing number of elderly people. Businessman Steve Vizard, who organised the conference, criticised the Government's failure to come up with a population target. 'Never in human history have human fertility rates fallen so fast, so far, over so much of the world,' he said. But environmentalists argued that Australia must first fix its environmental problems, including salinity, water shortages and greenhouse gas emissions, before planning a big population increase. Michael Krockenberger, from the Australian Conservation Foundation, said: 'Australia is an unsustainable country at a population of 19 million and will only be more unsustainable at any larger population.' Family welfare groups said the fertility rate would only rise if Australian women were given greater access to paid maternity leave and affordable child care. Among the most vehement critics of a big population expansion is New South Wales Premier Bob Carr, who fears most immigrants would end up in Sydney, putting an intolerable strain on an already overburdened infrastructure. 'People who talk about a population of 50 million for Australia are describing for Sydney a population of 10 million - I don't want to see that,' he said. Demography experts predict that with present levels of immigration, Australia's population will rise to about 25 million by 2050.