The French Polynesian assembly has adopted a formal declaration for a moratorium on any plan to allow seabed mining.
Forty-five members voted for, and 11 against the text, which aims to block any such activity until more is known.
It said there had to be evaluations to understand the risks of seabed mining to the environment.
The text said this was a precautionary approach which built on the principle that the polluter paid.
Nodule Collector Photo: Cook Islands Seabed Minerals Authority
In September, the advisory social and economic council had opposed seabed mining.
At the COP27 meeting in Egypt last month, the French President Emmanuel Macron called for a global ban on seabed mining.
The French government said such a ban was stronger than a moratorium and would also apply to France's exclusive economic zone, which includes French Polynesia's waters.
French Polynesia's EEZ is more than 4.7 million sq km and accounts for almost half of the water surface under French jurisdiction.