New Zealand's incoming conservative prime minister unveiled an unusual coalition government Friday, with a pair of long-time political adversaries set to take turns as deputy prime minister over the next three years.

Nearly six weeks after voters ended the six-year reign of the centre-left Labour government, new prime minister Christopher Luxon and his National Party have stitched together a three-way coalition with the conservative ACT party and populist New Zealand First.

The role of deputy prime minister will change hands halfway through the government's three-year term, with New Zealand First's Winston Peters holding the position first before passing the baton to ACT leader David Seymour.

It could prove to be a volatile mix, with Peters, 78, and Seymour, 40, having shown a willingness to trade barbs in the past.

Earlier this year, Seymour described Peters as "the least trustworthy person in New Zealand politics".

The pair had another famous spat on social media in 2020, culminating in Peters telling Seymour: "I reckon you'd last 10 seconds in the ring with me".

But on Friday, they were eager to put their old animosities to bed, with Peters, who will also serve as foreign minister, saying the two had "shaken hands" and were learning to trust each other.

Luxon, 53, was keen to hose down suggestions of friction between the two, saying the government would be "using the talents of both of these leaders".

"We've done something historic. We actually have three parties in a coalition government," he told reporters at parliament.

"The fact that they have 18 months each is important. I'm looking forward to working with both of them."

Luxon's National Party will be the biggest partner in the coalition, having won 48 of 123 seats at last month's general election.

The former airline executive will be sworn in Monday, with the new parliament to first sit on December 5.

Political veteran Peters was deputy to previous prime minister Jacinda Ardern as part of a coalition government formed with Labour in 2017.