Ngapuhi are being summoned to debate who has the mandate to negotiate the country's largest iwi's long-awaited Treaty of Waitangi settlement.
The Government says it recognises the mandate given to Tuhoronuku by 76.4 per cent of tribal members in 2011.
However, the issue is further splitting an already divided Ngapuhi, says kaumatua Kingi Taurua, who is inviting hapu to debate the issue at Te Tii Marae, Waitangi, on Saturday.
The Waitangi Tribunal is holding an urgent hearing into the granting of the Tuhoronuku mandate next week.
Treaty law expert Charles Hirschfield and other negotiation and law specialists would be at Saturday's hui.