The Waitangi Tribunal has warned Ngapuhi leader Sonny Tau over comments he has made about it.
Mr Tau is the chair of Tuhoronuku, the board mandated by the Government to settle the Ngapuhi claims.
He has publicly accused the tribunal of predetermining the outcome of an urgent hearing on the validity of that mandate.
In a memo this week, the tribunal's presiding officer, Judge Sarah Reeves, said statements of that type came dangerously close to contempt.
The judge said the tribunal expects an explanation from Tuhoronuku's lawyers by tomorrow.
The tribunal's challenge and contempt warning come as hapu prepare for the hearing in Waitangi next week.
