The nationalist New Zealand First Party won 7.2 per cent of the votes, leaving it with the balance of power in the formation of the next government.
New Zealand First leader Winston Peters told local media that knowing the facts "puts us in a better position to make judgements" but would only make a decision on which party to back after the final tally and after the results become official.
A complete count of the "special" votes in the New Zealand election is due today.
Jacinda Ardern said the final election count strengthened her party's "mandate for change" and negotiations with NZ First would now begin in earnest.More news: Putin Hosts Saudi King to Talk About Oil, Syria
Prime Minister Bill English will stay in office until a new government has been formed.
Shaw was the first political party leader to react, welcoming new MP Golriz Ghahraman, who came to New Zealand as a child and refugee from Afghanistan, and arguing for a "full coalition" with the Labour and New Zealand First parties to form the "first true MMP Parliament" since the country moved to proportional representation voting in 1996. The Green Party, at 6.3percent, lost nearly five percentage points on its 2014 tally following a disastrous start to its campaign when co-leader Metiria Turei resigned over self-confessed benefit and electoral system rorts.More news: Joe Girardi says he 'screwed up' by not challenging HBP call
"I remain as determined as ever to lead a strong, stable government for the next three years that will deliver on the hopes and aspirations of all New Zealanders", he said.
The new balance of possibilities means that if National and NZ First were to ally to form a government, the new government would have a notional majority of 11 seats, including Act.
"I don't think it weakens it significantly at all", referring to National's negotiating position.
English added he had known Peters a long time and the National party would not rule anything out before talking privately to Peters.More news: Aging robot arm gets spacewalk surgery
New Zealand First says it will hold discussions on Sunday with the National Party at midday and with the Labour Party in the afternoon. Parties receive seats in Parliament in proportion to their party vote share while seats are filled firstly by winning electorate candidates and secondly by candidates on the party's list. He wants to drastically reduce immigration and stop foreigners from buying farms.
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