Wellington - Three weeks from a general election, New Zealand's Labour-led coalition, which has governed for nine years, is headed for defeat at the hands of a conservative administration, according to an opinion poll published on Saturday.

The Fairfax Nielsen poll shows the opposition conservative National Party favoured by 51 per cent of committed voters, against 33 per cent for Labour.

The poll - of 1,160 voters nationwide, with a margin of error of 3.2 per cent - indicates that Labour has made no ground in the first week of the official campaign before the November 8 election.

It shows little change in voter sentiment from the same poll in April when the Nationals led 52-34.

National party leader John Key, a former money dealer who is the richest man in parliament, is the preferred prime minister for 43 per cent of voters, with Labour's incumbent Helen Clark behind at 35 per cent.

Of minor parties, only the Greens, favoured by 7 per cent of voters, are over the 5 per cent threshold needed to guarantee seats in the next parliament, though commentators say the Maori Party could make a clean sweep of the seven seats reserved for indigenous voters. (dpa)