Jacinda Ardern is next New Zealand PM after Winston Peters supports Labour Party government

New Zealand First leader Winston Peters said on Thursday he would support the Labour Party to form government after an inconclusive September 23 election, making Jacinda Ardern the country's third female prime minister.

"We had a choice to make... for a modified status quo or for change," Peters told reporters in Wellington, ending nearly a month of political uncertainty following the election which has hit the local currency and business sentiment.

"That's why in the end we chose a coalition government of New Zealand First with the New Zealand Labour Party."

New Zealand First holds the balance of power with nine seats, a Labour-Green bloc controls 54 seats, and the National Party 56 seats.

Peters' decision to back a Labour government ends nearly a decade of National rule.