The Office of Treaty Settlements has denied taking sides in a claims dispute between Tauranga's Ngāi Te Rangi people, and Hauraki iwi.
Ngāi Te Rangi has told the office to back off, after it emailed them, following an alleged assault on a kaumātua at a recent ahi kā event.
Ngāi Te Rangi said the email implied they were improperly digging holes and lighting fires - and Ngāi Te Rangi accused the office of being partisan.
The office has now apologised.
Director Lil Anderson said the email was poorly worded and unclear.
"We wrote to Paora Stanley of Ngāi Te Rangi Settlement Trust on Monday apologising [for the email]," Ms Anderson said.
"The email was sent to inform them of what we were hearing about possible trespass at a Treaty settlements landbank property, not to imply any sort of responsibility."
Tensions were running high between Ngāi Te Rangi and the Hauraki iwi, and Ms Anderson said she regretted that the office was perceived to be taking sides.
"We have a responsibility to work with all groups seeking to settle historical claims and take that very seriously," she said.
"We have worked in good faith with Ngāi Te Rangi and other Tauranga iwi for nearly 10 years now, and Hauraki iwi for almost that long. We understand and will continue to uphold the importance of impartiality in the work that we do."