WELLINGTON (AFP) - Polling booths opened in New Zealand's general election Saturday (Oct 17), with voters queueing at schools and community halls across the South Pacific nation to cast their ballots.

Prime Minister Jacinda Ardern is seeking another three-year term for her centre-left government, against an opposition led by the conservative National Party.

The popular leader is in striking distance of re-election with an unprecedented outright majority after campaigning on her success handling the Covid-19 pandemic.

Pre-election opinion polls put support for Ms Ardern's Labour Party at 46 per cent, 15 points ahead of the main opposition Nationals but just short of being able to govern alone.

Ms Ardern has dubbed the vote "the Covid election", saying she wants the chance to continue a virus response that has eliminated community transmission and seen just 25 deaths in a population of five million.

"Who's better placed to keep New Zealand safe and who's better placed to get us on track to recovery?" she asked repeatedly on the campaign trail.

Another theme has been "sticking together in uncertain times", highlighting the charismatic 40-year-old's leadership qualities, not just during the pandemic but in a series of crises during her three years in office.

These include the Christchurch mosques shootings in March last year, when a white supremacist gunman killed 51 Muslim worshippers, and the White Island (also known as Whakaari) volcanic eruption last December in which 21 people died.

"No matter what crisis is thrown my way, you will always be assured I will give my everything to this job, even if that means a huge sacrifice," she said this week.

Coalition and compromise

No leader of any political persuasion has achieved an outright majority since New Zealand adopted a proportional voting system in 1996, leading to a succession of multi-party governments.

If polling showing Labour's support in the mid-to-high 40s proves accurate, backing from Ms Ardern's existing coalition partner, the Greens, would comfortably get her over the line.

However, they may demand a more progressive agenda in return for keeping Ms Ardern in power, after a first term when she failed to deliver on some key promises such as improving housing affordability and countering child poverty.

Ms Judith Collins, the combative leader of the centre-right National Party, has focused on the spectre of the Greens forcing Ms Ardern to adopt a wealth tax aimed squarely at New Zealand's aspirational middle class.

Ms Collins, 61, sparked a rare flash of anger from Ms Ardern with the claims in a televised debate this week.

"I have been absolutely clear on this multiple times - it is a desperate tactic and frankly sad," said Ms Ardern of the wealth tax claim, also calling Ms Collins a liar.

The conservative leader, known as "Crusher" for her hardline policies when police minister in a previous government, was undeterred, saying National was best placed to steer New Zealand through a Covid-19 induced recession.

"I bring real business experience at a time of grave economic situation that we're moving into now, and the ability to make decisions," she said.

Virus election delay

About 3.5 million people are registered to vote, with 1.7 million, or almost half, casting their ballots early, a much higher figure than previous elections.

The vote was originally set for September 19 but was delayed by a virus outbreak in Auckland that has now been contained.

Ms Collins, who took over National in July after a period of turmoil when the party had three leaders in three months, said the false start had cost her campaign momentum.

National is polling at 31 per cent, which would be the party's worst electoral performance in 18 years.

The polls had Labour on up to 61 per cent in July, but even if the more recent 46 per cent proves correct, it would still be a 33-year high for the party.

New Zealand has strict election day laws that do not allow exit polls during voting, which begins at 9am and ends at 7pm.

Under the country's rules, media outlets are extremely limited on what they can report during the day, with election adverts similarly restricted, to prevent voters being swayed.

However, a firm indication of the outcome is expected within about three hours after polling booths close.

Voters also cast ballots in two referendums, one on legalising recreational cannabis and the other on legalising euthanasia, although the results of those votes will not be known until Oct 30.