NEW ZEALAND - Finance Minister Bill English has been selected as the country's new leader after the ruling National Party voted him to power in a special caucus meeting.

English's appointment follows surprise resignation of popular leader John Key.

English is a 54-year-old former farmer and practicing Roman Catholic who has degrees in commerce and literature.

Senior cabinet minister Steven Joyce will replace English as finance minister.

English, who was alone in the race, announced Social Housing Minister Paula Bennett as the deputy leader after the meeting in New Zealand's distinctive "Beehive" parliament building in Wellington.

The appointment of English, which was widely expected, came a week after John Key announced he would step down as the prime minister in a shock decision at the height of his popularity.

"I am both excited and humbled by this opportunity," English said.

He said he would continue developing the legacy of his predecessor.

"I'll also seek to build on the international recognition earned by John Key for New Zealand's increasingly distinctive place in the global community, as a successful economy open to trade open to investment and immigration.”

English has held several ministerial posts across education, health and finance since he joined Parliament in 1990.

As finance minister, his key policies included moves to partly privatise several state-owned energy firms and Air New Zealand, cutting personal tax and corporate tax rates and increasing the goods and services tax.

English voted against a successful same-sex marriage bill in 2013, but said as leader he would not pursue his own agenda.

"I'd probably vote differently now on the gay marriage issue. I don't think that gay marriage is a threat to anyone else's marriage," he said.

"But again I don't intend to use the position to try and influence those issues.”

With just one change of government so far this century and two prime ministers, New Zealand's political stability is in stark contrast to Australia's shakes and shifts, writes Philip Williams.

"They've been dealt with by the Parliament and by the process of law and I accept that."

Mr English, who 13 years ago oversaw a disastrous election loss for the National Party to the centre-left Labour Party, takes the reins of a country in good economic shape compared to much of the developed world.

On Monday, Moody's said it expected New Zealand to remain among the fastest growing of triple-A rated economies.

Mr English has already lined up senior cabinet minister Steven Joyce, the minister for economic development, to replace him in the finance ministry.

He is expected to announce further cabinet changes in the coming weeks and has also signalled a "stocktake" on policy.

- ABC