AUSTRALIA'S population growth is in free fall, with net immigration slumping 37 per cent year on year in the March quarter to its lowest level in years.

The Bureau of Statistics reports that net immigration plummeted from 98,138 in March 2009 to just 61,780 in the same quarter this year. It is the lowest figure for a March quarter since the bureau adopted new definitions in 2006.

Population growth in decline.

For the entire year to March, net overseas migration plunged by 25 per cent, from 320,362 in 2009 to 241,352 this year. Most of that fall was in the last six months, after the Rudd government closed the back door allowing foreign students in low-level courses to stay on as permanent migrants.

Opposition Leader Tony Abbott pledged in the recent election campaign to cut net overseas immigration to 170,000 by 2012. The bureau figures suggest most of that had already been achieved by March, with the trend suggesting further falls in coming months.