NZ First has gained support in the latest opinion poll which shows the party firmly placed to decide which of the main parties would form the government if an election was held now.

The Roy Morgan Poll has NZ First up three points to 10.5 per cent, it's highest level this year.

National has dropped half a point to 43 per cent, while Labour is unchanged on 29.5 per cent and the Greens are down 1.5 points to 13 per cent.

With a Labour/Greens alliance holding 42.5 per cent, NZ First would hold the balance of power in parliament and party leader Winston Peters would again be the kingmaker.

The results are similar to other polls this year, although most have shown National in a stronger position.