Prime Minister John Key says South Korea has acknowledged New Zealand should not be disadvantaged as a result of other free trade agreements it makes.
Mr Key is in South Korea on a 10 day trip, which includes visits to China and Vietnam.
A free trade agreement was at the top of the agenda when Mr Key met South Korean Prime Minister Chung Un-chan.
Australia, the United States and the European Union are also in the process of negotiating trade deals with South Korea.
Mr Key says the Prime Minister signalled it would not be fair if New Zealand was disadvantaged because of those other agreements and reconfirmed his country's desire to secure a deal.