A Tauranga iwi says the removal of containers from the crippled Rena may be another potential pollution risk to the environment.
The vessel ran aground on the Astrolabe Reef on 5 October, spewing hundreds of tonnes of oil into the ocean.
Maritime New Zealand says removing the containers will be complex, as the Rena's severe lean has buckled the locks that hold them together.
It aims to take more than 1200 containers off the vessel using a crane barge, but says it might be able to remove only five a day to begin with.
Te Runanga o Ngai Te Rangi chairperson Charlie Tawhiao worries the procedure may result in the contents of some containers seeping into the water.
He says some contain toxic substances, while others hold rotten food, some of which has already washed ashore.
