Ngati Ruapani in Te Urewera wants MPs to launch a full inquiry into the Tuhoe Treaty settlement.
A bill to put the Crown package for Tuhoe into law is being reviewed by the Maori Affairs Select Committee.
Ngati Ruapani ki Waikaremoana wants to know how an agreement between the Crown and Tuhoe to create a new entity for Te Urewera National Park will affect rights to Lake Waikaremoana.
A descendant of Ngati Ruapani, Vernon Winitana, is urging politicians to investigate.
His lawyer Kathy Ertel says officials in Wellington have made a fundamental mistake. She says the Crown has conflated the rohe (territory) of Tuhoe as being Te Urewera, the National Park. But Ms Ertel says the park is not only the rohe of Tuhoe - it's also the rohe of Ruapani.