A rise in work visa has been the driving force behind record immigration numbers but the main source countries are not from Asia.

A Herald analysis into immigration data found work visa arrivals increased from 16,787 in 2004 to 41,576 last year.

The top five source countries for work visas last year are the United Kingdom, Germany, Australia, South Africa and the United States of America.

The United Kingdom, which made up 16.6 per cent of work visas issued, has twice as many as those of Germany on 8.8 per cent.

Figures to be released today by Statistics New Zealand is expected to again show strong population gains, and possibly a sixth straight month of net migration gains exceeding 6000.

The gain in the year to February 28 hit a new record high of 71,333.

The government last week announced changes to policy to tighten immigration, focusing on changes in the work visa skilled migrant category.

Excluding New Zealand and Australian citizens, most arrivals in the year to February (43,025) were on work visas.

Of the total 128,816 arrivals, 16,833 had residence visas, 23,846 student visas, 6338 visitors and 694 others.

Despite China and India being among the biggest source countries for permanent residents, they are not among the top five for direct migrant workers.

Massey University sociologist Paul Spoonley said migrant from Asian countries were less likely to get direct access to New Zealand on skilled work visa.

"They are more likely to transition to permanent residence through temporary work and study visa routes using options such as the transition to work provisions," said Professor Spoonley, an expert on immigration.

"Given the penetration, and now ownership, by Australians of industries and companies, a significant component of Australian migration to New Zealand will involve middle and senior managers, as well as certain experts, for these companies."

One source which has seen a huge increase in work visas is South Africa, rising from 2.5 per cent in 2004 to 5.5 per cent last year.

"The South African arrivals remain cyclical and the numbers arriving will reflect certain push factors as well as the fact that there is now a well-settled local community," said Spoonley.

Between 2004 and last year, the Philippines increased from 0.4 per cent to 4.5 per cent, or from 71 to 1871 work visas.

In the same period, Chinese arriving on work visas increased from 312 in 2004 to 1697.

"Filipino workers are filling important niches in the New Zealand labour market, including in the health and farming sectors, especially dairying," Spoonley said.

But he said recent changes to immigration policy including the suspension of the parent visa category will likely reduce the numbers coming from Asian countries including China, India and the Philippines.

In the year to February, the number of Indian student visa arrivals had already dropped by 38 per cent.

On the rise, however, are the number of arrivals from the UK and the USA.

Also, as a proportion, work visas for Germans have increased from 3.1 per cent of the total in 2004.

"My guess is that we are starting to see the effects of Brexit and the Trump presidency as push factors," he said.

"There was an early hint of a new interest from these two countries in the expressions of interest figures post the Brexit vote and the confirmation of Trump as president ... they might displace arrivals from Asia if this upward trend continues."

Spoonley said high value immigrants from the UK and US will remain and important source of skilled migrants, and expected the numbers to trend upwards through the mid and later part of 2017.

The increase in work visas pushed net migration to a record 70,600 last year.

Migrant arrivals numbered 127,300, compared with 56,7000 people leaving the country. During the period, work visas were up 3800 to 41,600, but this was matched by a similar drop in those arriving on student visas.

The United Kingdom comprised the largest group of visitors planning to work here on nearly 7000, followed by France, Germany and Australia.

In March ASB had forecast net migration would hit 72,000 in the year to March 31, and the annual gain would continue to top 70,000 until the second half of next year. Drivers of net migration include 9000 more Kiwis returning home and 28,000 fewer leaving.

There's also been an increase in the number of Australians moving here, international student arrivals and 21,000 additional working holiday visa holders.

New Zealand's population is estimated to be around 4.77 million, according to Statistics New Zealand, and growth rates at this level would increase it to 5 million in 2019.

Recent moves by the government to tighten immigration policy include increasing the number of required points, toughening of English language rules and the suspension of the parent category.

Last week, the government announced migrants will need to earn more than $49,000 to qualify for the skilled migrant visa.

Immigration Minister Michael Woodhouse said the changes were aimed at increasing the quality of migrants, and not reducing numbers.

'I have what NZ needs'

Health worker Aeziel Niegos came to New Zealand in 2008 with a dream of settling here and becoming a Kiwi.

But the 39-year-old, who is earns $19.54 an hour as a house leader in an Albany health care facility, said changes to Immigration rules will make that an "impossible dream".

"The skills that I offer is what New Zealand needs, what I do, I do it well, and help New Zealanders with multiple disabilities," said Niegos, a qualified nurse from Ilcos Norte in the Philippines.

"I was planning to clear my last hurdle, the IELTS test, before I can lodge my application but now they have moved the goal posts."

Niegos' said her application to register as a nurse was declined by the Nursing Council in 2014 because she had been out of practice for five years.

"So I dedicated my life towards helping the aged and sick Kiwis, and I have really worked hard to get to my position as house leader" she said.

"It is my passion to help the old and the sick, and I believe there is so much I can give to New Zealand."

A significant number of workers in the health care sector here are from the Philippines.

A starting pay for a registered nurse is $22.60 according to payscale.com, still below the required amount to qualify under the skilled migrant policy.

Many Filipino caregivers working in rest homes, private hospitals and disabled care units, like Niegos, are not registered nurses and earn minimum wage or just slightly above.

"I am still keeping faith, and praying everyday, that common sense will prevail," said Niegos, a Roman Catholic.

"If all of us have to leave New Zealand, it could seriously cripple the health sector."