The Environmental Protection Authority has warned there is not enough information to consider granting consent for New Zealand's first offshore iron sands mining project.
Trans-Tasman Resources (TTR) wants to mine almost 66 sq km of seabed off the south Taranaki coast.
After two months of hearings around the North Island, the EPA produced a report for consideration over whether to approve or decline marine resource consent.
It says there is uncertainty about the impact the mining might have on the environment.
It also says there isn't enough information on how to manage any adverse effects from such a project.
The chair of Kiwis Against Seabed Mining Phil McCabe said the report validated his organisation's concerns and he did not believe a marine resource consent will be granted.
"TTR, after two months of hearings, have not been able to prove that they can do it in an environmentally safe way. And we do not see how the decision-making committee can come back with any result other than denying TTR's bid."
The consent application is the largest to be considered by the EPA since it was established in 2009.
The hearing ends on Thursday and a decision is due in early June.