The Ministry of Economic Development is defending aerial surveying for minerals on the South Island's West Coast.
The Government intends to conduct further aero-magnetic surveys of the land from Haast through to Karamea.
This will include areas of Te Wahipounamu, a world heritage area, but not the Fiordland, Mt Aspiring and Aoraki/ Mt Cook national parks.
But the Ministry says the surveying does not include high value Schedule Four conservation land.
Ministry spokesperson Tracy Dillimore says any World Heritage Area land will never be mined.
However, Labour's conservation spokesperson Ruth Dyson says the only reason for the investigation of mineral deposits is the future potential for exploration.
Green MP Catherine Delahunty said world heritage areas should be entirely off limits to mining and placed under Schedule 4 protection.
She said the survey indicates the Government is prepared to mine the area.
But the prime minister, John Key, has given his assurance that no mining will take place on Schedule Four or World Heritage Land.
Mr Key said on Monday that people should not have any concerns.
"In 2010 I spelled out very clearly that we wouldn't be going into Schedule 4 land or World Heritage sites. The reason that survey work is being undertaken is, as I understand it, because there are many other benefits that may flow from that data collection."