Cook Islands paramount chiefs are opposing a proposed development on Rarotonga's Avana foreshore.
The area is home to a marae belonging to the Ariki line of Kainuku.
The cultural, historical and environmental significance of the area was the subject of a recent presentation to the House of Ariki by environmentalist Liam Kokaua.
Mr Kokaua said the paramount chiefs would be formally submitting their opposition to the National Environment Service and Rarotonga Environment Authority.
The chiefs wanted to strengthen their involvement in the vetting process for development projects on Rarotonga, he said.
The House of Ariki wanted their role as mana tiaki or stewards of land and sea to be strengthened, the environmentalist said.
The Environment Impact Assessment report on the proposed development is widely considered flawed as it states the Avana foreshore land has no cultural or historical significance.
An online petition protesting the development already has the backing of 1100 people.