As Australia's mining-investment boom winds down, the central bank has been relying on a steady flow of new migrants to boost the economy -- a stimulant most developed nations lack.

But the country's appeal is now waning as wages stagnate and its jobless rate climbs above the US level. The population is on track for the slowest growth in nine years -- a danger signal for an already faltering economy.

Australia's population growth slowed to 1.4 per cent in 2014, down from 1.8 per cent two years earlier.

"It's another challenge for policy makers already struggling with a difficult situation," said James McIntyre, head of economic research at Macquarie Group and a former Treasury official. "On the monetary policy side, it really amps up the pressure."

An expanding population and record-low interest rates are lynchpins for the Reserve Bank of Australia's forecast that growth will pick up to its long-run average of about 3 per cent. Without rising ranks of new workers to boost consumption and buy the growing number of newly constructed houses, the economy's recovery is that much trickier.