WELLINGTON (REUTERS) - New Zealand Labour leader Jacinda Ardern said on Sunday (Sept 24) it would be difficult to complete coalition talks before all votes were tallied in an election that left both major parties needing the nationalist New Zealand First party to form a government.

Speaking outside her home in Auckland, Ardern told media that her centre-left party would not concede, despite lagging almost 10 points behind the incumbent National Party, which received 46 per cent of the vote in Saturday's election.

A final tally of all votes, which will include overseas ballots, will not be released until Oct 7.

New Zealand First leader Winston Peters has declined to say which party he will favour to form a coalition government and reiterated that he will not rush into a decision.