The ACT Party has announced it will prioritise productivity over everything else, if elected.

ACT leader David Seymour has unveiled a policy that would set a target for New Zealand to be one of the OECD's top-10 fastest growing economies, measured by GDP.

It comes the same day as ACT reaches new heights in the Roy Morgan poll - they're up to 18 percent support, behind National on 31 percent and Labour on 24 percent.

ACT leader David Seymour spoke to Charlotte Cook.