MPs are asking the Office of Treaty Settlements to investigate the extent of an iwi's tribal territory.
A map shows the whenua (land) was submitted by Ngati Raukawa as part of the Raukawa Claims Settlement Bill and was accepted by the Crown.
Te Arawa River Iwi Trust says Ngati Raukawa is claiming an association with land and waterways that goes way beyond its traditional rohe (district).
Trust representative Robyn Barge says if an individual of Ngati Raukawa can claim an interest in a piece of land then the iwi itself can claim an interest or association with it too, even when that individual's claim is through other avenues.
Ms Barge says the Crown is most to blame for letting the map be part of the treaty settlement.
She says Ngati Raukawa is being mischievous to start claiming more interest in land than it really has and is indulging in a modern-day form of imperialism.
Ms Barge says the map's inclusion is very contentious and has implications not only for the Te Arawa River Iwi Trust, but other iwi as well.