David Parker is off to Argentina this weekend for a major ministerial trade conference.

The Trade Minister says he will be making an effort there to secure better rules under the World Trade Organisation to limit subsidisation of agriculture and fisheries.

Subsidies for farmers and fishers in other countries make it harder for New Zealand exporters - who don't get the same subsidy - to stay competitive.

Mr Parker says that's his main focus in Buenos Aires, continuing New Zealand's efforts at the previous two World Trade Organisation ministerial meetings in Bali in 2013, and Nairobi in 2015.