Australia's population has expanded rapidly over the past 12 months, boosted by the record number of immigrants settling into the country, according to the Australian Bureau of Statistics.

Over the year to September 2007, total population grew by 1.5% to 21.097 million people - the fastest growth rate in 18 years. Net overseas immigration rose sharply by 179,100 - contributing more than half (56%) of the total population growth over the past 12 months. There were 278,500 babies born in the same period - a 5.8% increase from the previous year.

Nationally, Western Australia recorded the fastest population growth at 2.4%, followed by Queensland and the Northern Territory which both achieved a 2.2% increase. Victoria and the ACT added an average of 1.5%, while NSW and South Australia saw their populations grow by 1%.

Queensland remained the top choice for interstate migrants with 102,200 people (almost 2,000 per week) moving to Queensland from other states and territories. This resulted in a net gain for Queensland of 27,000 people.

"The remarkable lift in Australia's population has significant consequences for the economy," said Savanth Sebastian, equities economist with CommSec. "The faster rate of population growth means that the economy can grow at a faster pace without lifting the rate of inflation or necessitating higher interest rates."

The increase in skilled immigration will help address the ongoing labour shortage and boost general retail spending, according to Sebastian. However, he warned that this sharp increase in population growth would put further upward pressure on the demand for housing.

"While the supply of housing remains far short of demand, we are seeing that the housing sector is slowly starting to build more homes. The rental market is the tightest in 18 years and can't get much tighter. The strength in rental yield and a more uncertain outlook for the share market is likely to see more investment in housing over the coming months."