The Democratic Party of the Cook Islands is backing a call by some Pacific countries and civil organisations for a 10-year moratorium on any seabed mining activity.
The opposition party said there were too many unknowns about the seabed and long-term impact of mining it.
Party leader Tina Browne said a precautionary approach would afford Pacific island countries, including the Cook Islands, time to gather and learn from more scientific data.
Ms Browne is urging the government to be completely transparent and cautious about any ventures to exploit the local seabed to harvest stocks of manganese nodules concentrated in the South Penrhyn Basin.