New Zealand's annual net migration fell in May as the number of foreigners arriving stayed the same but the number of New Zealanders and foreigners leaving rose.

Annual net migration was at 66,200 in the year to May, from 72,000 in the year to May 2017, Statistics New Zealand said. A net 67,600 foreigners immigrated to New Zealand in the May year, while a net 1,400 Kiwis left the country.

The number of non-New Zealanders migrating here was virtually unchanged from the year earlier, at 130,200 from 130,400 in the year to May 2017, but the number of non-New Zealanders leaving rose 9.5 per cent to 64,000 in the year. That's the highest level of migrant departures since May 2014, Stats NZ said.

New Zealand has been experiencing record levels of net migration in recent years, which made rising immigration a key election issue as it strains the country's infrastructure and is blamed for inflating property markets.

Net migration peaked at 72,400 in the July 2017 year, and Stats NZ said today that annual net migration continued the general downward trend from then "mainly driven by an increase in migrant departures."

Increasing numbers of migrants came on work visas in the latest year, up 4.7 per cent to 46,500 from the previous year to May, with residence visa numbers down 16 per cent to 14,100 and student visas dropping 0.3 per cent to 23,700.

The United Kingdom remained the biggest source of work-visa migrants, though that number dropped 0.2 per cent to 7,400 in the latest year, as did the second and third-largest sources France and Germany which respectively dropped 3.5 per cent and 8.1 per cent.

The biggest increases in work visa arrivals came from the Philippines, which rose 23 per cent to 2,500 in the year, and China, which was up 21 per cent to 2,300.

China continued to be the biggest source of migrants on residence visas, though that dropped 20 per cent to 2,700 in the year.

Chinese migration remained the largest on a net basis, with 8,300 of net arrivals coming from China, though that was down 19 per cent on a year earlier. India was the second-largest source at a net 6,800, though Indian net migration was also down 11 per cent from a year earlier.

Short-term visitor arrivals, which includes tourists, people visiting family and friends and people travelling for work, reached 3.8 million in the April year, up 6 percent from a year earlier.