Infometrics economist Benjamin Patterson said that over the three months to April, the number of people arriving from Australia was up 29 per cent from a year earlier, the fastest growth since 1990. Over the same period, departures to Australia dropped 19 per cent.
"In the March quarter, the Australian unemployment rate reached its highest level since 2009, 5.6 per cent, while New Zealand's fell to a three-year low of 6.2 per cent. The relative performance of the two labour markets is a major factor driving the change in migration flows," he said.
Westpac economist Felix Delbruck said that in recent months there had been a pick-up in migrants from Europe and the United Kingdom in particular, reflecting in part the labour requirements of the rebuilding of Canterbury.
"Monthly net immigration to Canterbury rose further and is now the highest since 2004," he said.
"Outside the region net immigration is also back in positive territory and rising, albeit still fairly modestly."
ASB economist Daniel Smith expects the trend of an easing net outflow across the Tasman to continue as the New Zealand labour market improves.
"Net migration inflows will place further strains on supply-constrained housing markets in some areas of the country. For now, the impact will likely be marginal as the inflows remain fairly small. By comparison, inflows of 3000 or 4000 a month were seen regularly in the early to mid-2000s," Smith said.
The Treasury in last week's Budget forecast net immigration to rise to 12,000 on an annual basis by the start of 2015.