Australia's economy will deteriorate and inflation rise if the admission of skilled migrants is not maintained at least at its current level, according to some of the nation's most prominent business figures.

The population debate began on June 27 when Prime Minister Julia Gillard rejected Kevin Rudd's "big Australia", saying her government would no longer be rushing towards a target of 35 million Australians by 2050.

''The boom in retirees means there is a bust in the number of working Australians, '' said Challenger Financial Services chief executive Dominic Stevens.

''As Bernard Salt [demographer at KPMG] says, there is a demographic fault line running through the Australian workforce.

''If not addressed, in the next few years our annual net growth in working-age population will drop sharply ... We definitely need to be cognisant of this change and must manage the effects.''

One of Australia's most powerful mining magnates bluntly rejects Gillard's campaign promise to slow migration target.

''If you stop Australia growing then you stop the economy growing and you stop the aspirations of every single Australian growing,'' said Fortescue Metals chief Andrew ''Twiggy'' Forrest.

Myer chief executive Bernie Brooks would also ''love to see'' the country's population swell, especially in regional areas.
''If I take Townsville, there are 170,000 people in Townsville in a region that comfortably could take another 100,000 people because of the infrastructure that has been built,'' he said.

''It's a matter of who is prepared to be proactive and logical in allowing migrants to come in with the skills and to the locations where they are most needed.''

The business community, however, is in furious agreement that the country's infrastructure and training programs must be better planned to aid economic expansion.

Len Ainsworth, founder of poker machine group Aristocrat Leisure and one of Australia's wealthiest, has warned that the country must be careful to balance population growth with infrastructure availability.

With his company based in Sydney's overcrowded inner west, Mr Ainsworth complained New South Wales roads were so inadequate that a flow of immigrants would not be desirable. "We have a growing population. I don't think it is something we should bring forward," he said.

According to him, there was a need to guard the country's borders so it could filter and choose the right immigrants. "We should be concerning ourselves with the quality of the immigration," Mr Ainsworth said.