A lawyer representing iwi says Rena's owner and insurers are not disclosing the full details of assessments on the potential environmental impact associated with leaving the wreck on the reef.
Director of North South Environment Law Robert Makgill said information received by iwi from assessments carried out by the Swedish Club was "very scarce and full of gaps".
Mr Makgill represents Bay of Plenty iwi affected by the Rena's Astrolabe Reef grounding and unless the club made more effort to engage with iwi, it would end up in the Environment Court, he said.
"Because you are dealing with people who see themselves as spiritual guardians of that environment, they just feel like the are being drip-fed very dumbed down bits of information."
Mr Makgill said he and a team of experts were unable to advise iwi in their response to whether Rena should stay on the reef, because of a "dearth of information".
"We have had a couple of reports that seem to favour the option of leaving it there but there's a whole lot of reports referenced that we haven't seen.
"This is the concern. They come out sounding very credible about how this is the best option but there's not the information to support that," he said.
Community consultation meetings set up for next week by the Swedish Club were described by Mr Makgill as "a controlled release of information as a public relations exercise".
Environmental marine scientist Dr Shaw Mead said the information they had already received appeared to be lacking in the most important aspects, including the alternative wreck options and environmental effects.
Cultural adviser Buddy Mikaere said there had not been much engagement with local kaumatua on Motiti Island, or on the mainland.
Mr Mikaere said the group was strongly opposed to leaving the Rena on the reef.
The Swedish Club spokesman Hugo Shanahan said iwi groups already had available draft assessment reports from which they planned to get feedback from the wider community.