Prime Minister Jacinda Ardern is promising that this year's election will not descend into mudslinging and scrapping, telling Labour MPs and media Labour will run a "positive campaign" in 2020.

She also revealed that some of the Government's previously announced $12 billion infrastructure package will be spent on New Zealand's fight against climate change.

Ardern was speaking to media and Labour MPs at the party's annual retreat in Martinborough – it's one of the few times she has spoken publicly this year.

While she said her Government would continue to focus on governing this year, she acknowledged that the "election campaign looms large for everyone in New Zealand".

She used the opportunity to outline what kind of campaign the Labour Party planned on running.

"[Labour] wants a positive campaign, a factual campaign, a robust campaign. [These] are all values and principles that were really important to us in the last election, and will be central to us this election."

She emphasised that Labour would run a "factual campaign", unlike some of recent elections seen overseas.

"[It is] incredibly important for us as the Labour Party that New Zealand does not fall prey to what we have seen happen in other jurisdictions."

She did not, however, outline which countries she was referring to.

Labour would be running an election that was "free from misinformation where people can make honest reflections for themselves about what they want for the future of New Zealand".

She said New Zealanders "deserve that kind of election campaign".

Ardern also teased new elements of the Government's $12 billion infrastructure fund.

The Government announced last year that it would be borrowing more money while interest rates were low to pay for some "significant" infrastructure projects.

So far, just one project – $400 million into New Zealand school development – has been announced.

But Ardern this morning revealed that some of the $12 billion will be going towards fighting and mitigating the effects of climate change.

The fund, she said would have a "particular focus on decarbonisation".

"That's a nod to the fact that we recognise that with this infrastructure package, we need to future proof New Zealand's economy."