National has widened its party-vote lead over Labour and the governing parties remain above the majority requirement in the official projection, but a string of close electorate contests keeps the outcome unsettled.

Official Electoral Commission figures at 10pm put National on 554,491 party votes, or 29.44 percent, against Labour's 550,873, or 29.24 percent. National's lead was 3,618 votes, up from 389 at 9.45pm.

National, ACT and New Zealand First had 67 projected seats in a 130-member Parliament, where 66 would constitute a majority. National had 42 seats, ACT 13 and New Zealand First 12.

The projected House had shrunk by one seat since 9.45pm, with the Greens dropping from 17 seats to 16. Labour remained on 35, the Opportunity Party seven and Te Pāti Māori five. Those four parties together totalled 63 seats, without an agreed governing arrangement being established by that arithmetic.

Nationwide, 62.6 percent of voting-place results had been counted, covering 1,883,444 party votes.

Hamilton East remained exceptionally close. National's Ryan Hamilton led Labour's Georgie Dansey by 39 votes, with 65.3 percent of results counted. The seat had repeatedly changed leaders earlier in the evening.

National's Carlos Cheung was 194 votes ahead of Labour's Michael Wood in Mt Roskill, with 44 percent of results returned. All of National's projected seats came from electorates.

Wellington Bays was tightening. The Greens' Julie Anne Genter led Labour's Craig Renney by 346 votes, down from 611 at 9.45pm, with 67.6 percent of results counted.

Labour's Kieran McAnulty was 278 ahead of National's Mike Butterick in Wairarapa, where 54.1 percent of results had been returned. Ginny Andersen led National's Chris Bishop by 504 in Hutt South, with 62.5 percent counted.

In Nelson, National's Blair Cameron led Labour's Rachel Boyack by 1,048 votes, with 87.2 percent of results counted. Labour's Tracey McLellan was 1,913 ahead of National's Vanessa Weenink in Banks Peninsula.

National's Katie Nimon led Alex Hedley by 5,151 in Napier, with 70.3 percent of results counted. Catherine Wedd was 7,715 ahead of Dan Scott in Tukituki, where 68.5 percent had been returned.

On the nationwide party vote, the Greens had 13.64 percent, ACT 10.90 percent, New Zealand First 9.64 percent and the Opportunity Party 5.73 percent. Te Pāti Māori had 0.57 percent and led in five electorates.

Opportunity leader Wong was celebrating the prospect of entering Parliament. RNZ reported at 9.36pm that Wong had told supporters it was looking very likely the party would make history that night.

The count remains preliminary. Special votes are counted after election night and can change electorate margins and the allocation of seats.