Te Runanga o Ngati Ruanui Trust has blasted a decision to extend the hearing into Trans Tasman Resources' plan to mine ironsands from the seabed off South Taranaki.
The Environmental Protection Authority (EPA) hearing was due to finish on March 20 but has been extended until May 31. It then has 20 days to make a decision.
The EPA delayed the completion date after more investigation was needed into sediment plume modelling, and working out worst case scenarios.
Te Runanga o Ngati Ruanui kaiarataki Debbie Ngarewa-Packer said the trust along with the several fisheries organisations, including Talley's Group Limited and
Fisheries Inshore New Zealand, opposed the extension because it "unreasonably added cost, time and effort to an application that was already seen as inadequate".
She said there had been "a clear one-sided advantage throughout the whole process".
Ngarewa-Packer said there was an allowance under law to extend the hearing but the scales were tipped in the wrong direction.
"Trans Tasman Resources are set up to focus on one thing, while the hundreds who oppose this can only draw on a finite amount time and money.
"As it stands, TTR have failed to dispel any of the uncertainties brought up during the hearings to date.
"So why give them more time to address the numerous gaps in their own information?
"If it doesn't stack up now the project should be rejected outright."
She said the delay was another "questionable act by the EPA" which had previously "refused to hold the hearings in the area that would be affected most".
It had also wrongly redacted information, she said.
•Caution essential, Ngā Rauru tells seabed mining hearing
•Ngati Ruanui blasts EPA decision to extend seabed mining hearing
•Fish stocks and high emotion at seabed mining hearing
•Seabed mining petition presented at Parliament
Te Runanga o Ngati Ruanui chairman Haimona Maruera Jnr said it "appeared the authority was doing everything it could to get the project over the line".
"Moving the goal posts to suit one side is shameful and highlights the unfortunate trend of playing games with our community's future."
He called the process "shambolic and often confusing".
"....we have lost all faith in the EPA and doubt it can uphold the fairness the authority should stand for.
"Our people have fought hard and fairly, yet the burden is again placed on us to exhaust further time, money and effort to protect our rights," Maruera said.
In announcing the extension, EPA chair Alick Shaw said its Decision Making Committee (DMC) had taken into account the interests of the parties to the hearing, including the additional time and costs.
"However the DMC is conscious of its obligation [under law] to base its decision on the best available information and consider that the extension serves the interests of the community in ensuring that the DMC is able to achieve an adequate assessment of the application."
He said the DMC "thanked all parties for their contributions to the hearing up to this point.
"The DMC have received a considerable amount of information and heard a wide range of views from a large number of submitters and expert witnesses.
"Much time, effort and thought has gone into the evidence and representations that have been heard," Shaw said.