Wellington - New Zealand's opposition conservative National Party is headed for a landslide victory over the sitting Labour-led coalition in the general election scheduled for November 8, according to an opinion poll released on Sunday.

The Television New Zealand One News poll showed the Nationals winning 66 seats in the next parliament, enough to rule alone despite a voting system that encourages coalition governments.

Labour would have 43, the Greens six, the Maori Party four, the free market ACT party three and the United Future and Progressive parties one each.

The Nationals were supported by 53 per cent of voters with Labour on 35 per cent, according to the poll, the first released since Prime Minister Helen Clark announced the election date on Friday.

Clark, 58, a political veteran who has held the reins for nine years, trailed political tyro John Key, 47, by 31-40 per cent in a poll for most-preferred prime minister candidate.

The nationalist New Zealand First party, led by Winston Peters, who has stood down pending a number of inquiries into secret donations, would be wiped out, according to the poll. It is the third-largest party in the current parliament.

The Greens were the only minor party to register the 5 per cent of voter support necessary to guarantee seats in the House of Representatives.

The poll of 1,000 voters has a margin of error of 3.1 per cent. It was conducted between September 6 and Thursday night - the day before Clark announced the election date. (dpa)