News: UPDATE 1-NZ's Labour widens lead versus National in latest poll

(Adds detail from poll, debate)

WELLINGTON, Sept 7 (Reuters) - New Zealand's newly invigorated Labour Party has widened its lead over the governing National Party, further threatening its decade-long hold on power in a Sept. 23 general election, according to a poll on Thursday.

National fell 2 points to 39 percent, while support for the opposition Labour Party was unchanged at 43 percent, a poll released on the website of the 1 News broadcaster showed.

Jacinda Ardern has almost single-handedly changed the chances of the Labour Party since taking over as leader last month, with her charisma and popularity offsetting some criticism over vague tax plans and tighter immigration policy.

The New Zealand dollar fell to the day's low of $0.7176, having stood at $0.7207 shortly before the poll results were released. Support for Labour overtook that of National in a similar poll released a week ago.

The results come as Ardern and National leader Bill English faced another heated political debate - the third in a week.

English said he was not particularly worried about the poll results, while Ardern reiterated that her first call would be to the Green Party, with which she has a working agreement if she was in a position to form a coalition government after the vote.

The poll showed support for the New Zealand First Party rose 1 point to 9 percent, still tipping it as a likely kingmaker after the election. Support for the Green Party remains at 5 percent.