There's concern a new free trade deal with Korea could block any future attempts to block non-residents from buying New Zealand homes.

Labour believes the wording of a agreement could guarantee its citizens open access to New Zealand homes.

Its trade and export spokesman David Parker points out at the moment you can restrict the sale of farm land to foreigners, which New Zealand currently does.

Parker is concerned the new FTA may prevent future governments from cracking down on foreign buyers, or introducing a stamp duty when they purchase land.

"We think you should be preserving the rights of future governments to ban the sale of residential land as well," he argues. "I don't think it's right that the National government puts any barriers in the way of the future government wanting to ban the sale of houses to overseas people."

The FTA with Korea was announced and signed in November and some amendments will need to be made to existing New Zealand laws in order to align with the promises of the agreement. It is currently before select committee.