A growing outflow of people to Australia continues to curtail the population gain from net migration.

In February the net inflow of permanent or long-term migrants, including returning expatriates, was 2172, or 470 when seasonally adjusted, Statistics New Zealand said.

While that is up marginally on the net gain of 440 in January, it is well below the average monthly gain of 700 over the previous year and the average of 1000 a month over the past 20 years.

In the first two months of this year the net outflow of people to Australia has averaged 3280, up from a monthly average of 1850 in the last three months of 2010.

In the year ended February the net population gain from migration was 8200, down from 21,600 the year before and one-third lower than the average 12,000 over the past 20 years.

The main sources of arrivals were Australia (15,700, two-thirds of whom were New Zealand citizens), Britain (14,200), India (7300) and China (6600).

"Given the upheaval in Christchurch following the earthquake on February 22, and the relative strength of the Australian labour market and incomes, we think that the weakening trend is likely to be sustained over the next year or two as gross outflows continue to trend higher," Deutsche Bank chief economist Darren Gibbs said.

"We would not be surprised to see the annual net inflow fall to zero over the coming year."

(Source NZ Herald, Brian Fallow)