Prime Minister John Key has defended the Government's immigration policy, saying elderly immigrants pay more in tax than they get back in Superannuation.

NZ First leader Winston Peters yesterday called for New Zealand to take a hard look at elderly immigrants who get Super despite never contributing to the scheme through taxes.

"New Zealand has the most generous superannuation scheme in the world for recently arrived immigrants," he told about 200 party faithful at NZ First's annual conference in Palmerston North.

"An immigrant can arrive here at the age of 55, pay no direct tax for 10 years, and receive full New Zealand super at age 65."

Peters singled out a "young couple from China" who could bring in four elderly parents and after a decade here would be eligible for full super and free healthcare "that New Zealanders work hard for all their lives".

Peters told reporters there were 22,000 elderly immigrants from countries with no reciprocal pension agreement with New Zealand.

The figure came from "a very senior Chinese source" in a research group within the Chinese community but was not all Chinese nationals, he said.

Key this morning said the figure could be correct.

The Government had tightened the law around family reunification.

"We've got a slightly different test which looks at your ability to be self sufficient." he told Newstalk ZB.

Immigrants paid $3.3 billion a year in taxes.

"If you look at the taxes they pay when they come to New Zealand vis-a-vis what they receive from Superannuation or benefits and the like, it's billions more that we get paid than they receive."

Key said he was pro-migration.

"As long as people come to New Zealand with the right attitude, we're a stronger country because of it.

"They are a net stimulus to the country in terms of more people, more skills and they make a massive financial contribution."

The NZ First leader's attack on elderly immigrants was an attempt to beat up an issue to "get on the news".

Peters criticised other political parties for being too "barren" to raise the issue, but stopped short of saying immigrants shouldn't get Super.

- © Fairfax NZ News