John Key has confirmed that if New Zealand voted to change its national flag in this month's referendum, that flag would be used at the Rio Olympics in August.

Voting has now started in the second flag referendum and the final result will be revealed on March 30.

Mr Key said that if New Zealanders chose the alternative flag, the transition would not occur overnight but it would be relatively quick.

The Flags and Emblems Act would have to change, but this only required the Royal Assent and not a Parliamentary debate.


The changeover would definitely take place before the Olympics, he said.

"The expectation is it would be the flag that is used at Rio.... The advice I've had is it would be ready."

Mr Key said that whatever the result of the referendum, he hoped New Zealanders would embrace their national flag. One of the positives of the process had been that more people were flying flags outside their homes and in public, he said.

"A very sad and tragic day"

Prime Minister John Key paid tribute to Crowe this afternoon.

"Today is a very sad and tragic day, not only for Martin Crowe's family but for New Zealand and indeed for the sport of cricket.

"He is a New Zealander who had a fan base not only right across the country but in fact right across the world.

"I think he'll be remembered for his remarkable talent, for the incredible 299 he scored against Sri Lanka, and for having the most number of centuries that a New Zealand batsman has scored.

"But most of all, people's hearts were touched by the battle that Martin Crowe had with leukaemia [and] his burning side desire to be there for the first game of the Cricket World Cup ... In New Zealand.

"Our great sympathies go to Lorraine and his children."

Prime Minister John Key says today is a very sad and tragic day, not only for Martin Crowe's family but for NZ and indeed for the sport of cricket.

Clinton or Trump? Key won't say

The Prime Minister would not give his preference out of the two presidential frontrunners Hilary Clinton and Donald Trump today.

Although he had an established relationship with Clinton, it was his responsibility to work with whichever president the US chose, he told reporters.

Trump has publicly opposed the 12-country Trans Pacific Partnership.

Mr Key believes his stance could change if he entered won the top job.

"Whether it means it would be his policy if he was president would be a different issue," he said.

But Mr Key also said he was hopeful that the agreement was passed into law in the US before the election.

The TPP needs the backing of both the US and Japan to be ratified.

A small crowd of anti-TPP protestors followed Mr Key during his visit to Palmerston North today.

Around 15 people, some dressed as pirates, held placards that said "TPP - NZ RIP" and shouted anti-TPP chants as he visited Palmerston North Girls High School and Massey University.

Mr Key told a group of high school students that the protestors were misinformed and did not have a good understanding of what they were protesting against.

"They probably don't even know what the acronym [TPP] stands for."