New Zealand's record inbound migration has undermined the country's squeaky-clean reputation because of an inflow of people from countries where corrupt practices are the norm, according to the Serious Fraud Office.

Director Julie Read told Parliament's law and order committee that immigration to New Zealand "has bought other cultures which take a completely different view in relation to conduct we consider to be corrupt, and which has not historically been considered corrupt elsewhere."

Ms Read was responding to questions from MPs about New Zealand's worsening position in international anti-corruption rankings, three weeks after Transparency International's annual corruption perceptions index showed New Zealand falling to fourth in global rankings, having previously ranked as least corrupt for seven years running.

"It's bringing in an element we need to be aware of and we need to work within those areas of our society to make sure that doesn't take root here," she said.

Net migration to New Zealand has increased, with a record net gain of migrants in 2015 as fewer Kiwis leave and increased rates of inbound migration. That's been led by countries where bribery to speed up government services is often seen as the norm.

Ms Read told BusinessDesk that immigrants from India and China, which ranked 76th and 83rd respectively on international corruption rankings in 2015, had different cultural attitudes toward corruption.

"In places like India and China, a long time ago public servants weren't paid for their work by the government," Read said. "They received the payment for the licence they gave and that was where they were intended to get their income from, so you can see how those cultural backgrounds can in the long term play into different attitudes."

Indian migrants arriving permanently or for a long-term stay rose to 14,490 in 2015, or 11.9% of all long-term migrants that year, from 7509 in 2010, which was 9.1%. Migrants from China rose to 11,036 in 2015, up from 6177 in 2010, and increased on a proportional basis from 7.5% percent to 9.1% in that time.

(BusinessDesk)