A consents hearing has been told the company wanting to mine the seabed off the coast of Taranaki for iron ore may not have the correct resource consents.
Trans-Tasman Resources wants to mine almost 66 square kilometres of seabed between 22km and 36km off the coast of Patea in south Taranaki.
Mining could produce about 5 million tonnes of iron ore concentrate each year worth about $440 million.
The Environmental Defence Society told the hearing on Tuesday the company had applied for consents for mining under the new Exclusive Economic Zone legislation.
But its lawyer, Rob Enright, told the Environmental Protection Authority the application did not cover the waste - in the form of a sediment plume - that might float into the 12-nautical mile territorial zone. He said that would come under the Resource Management Act.
The authority said it would provide legal advice on whether it was a cross-boundary issue over the next fortnight.