A former advisor in the Kiingitanga has unleashed an unprecedented attack on the Māori King Tuheitia.
Tukoroirangi Morgan has written a scathing email criticising King Tuheitia's leadership skills - calling him a "puppet".
"Our people see you as a 'puppet' King," he said.
"Some of the public and often 'off the cuff' speeches you made were embarrassing because you are a poor communicator."
Mr Morgan was a trusted advisor to King Tuheitia until late last year.
He said the King publicly criticised him at the Iwi Chairs dinner at Hopuhopu just over a week ago, which prompted the email.
Most of the criticisms are directed at the King's chief advisor Rangi Whakaruru, and criticises his high salary, spending and management.
"How can Rangi justify his $250,000 salary, his $100,000 leased SUV, and his ability to have all his expenses reimbursed by the office.
"Rangi pulls the strings and you dance to his tune. It's despairing because it's destroying the credibility of the Kiingitanga."
The Serious Fraud Office is currently investigating the Ururangi Trust, which is a charitable trust connected to the office of the Māori King.
Late last month, the SFO raided the King's Waikato Offices and took documents and hard drives.
Mr Morgan claimed the investigation is focusing on Mr Whakaruru, and is calling on the chief advisor to be sacked.
"I mistakenly thought that you could unite and lead the Māori Nation across this country but with Rangi Whakaruru at your side you are doomed to fail."
Mr Morgan did not respond to RNZ's calls and messages today.
Sir Wira Gardiner said in a text message:
"As is well known, the SFO continues to investigate aspects associated with the King's office," he said.
"Until such time as they report, we will certainly not be commenting on any such matters or allegations."
He said Mr Whakaruru was not commenting today and that Mr Gardiner's response was for the King's office.
Waikato-Tainui MP Nanaia Mahuta said Mr Morgan was close to the King and the letter raises concerns.
"Evidently he held a position of trust within the tribe and on behalf of the Office of the King, those matters need to be resolved," she said.
"The tribe is looking seriously at many things that were said any many more things are being considered by the SFO."
Ms Mahuta said there is anxiety amongst tribal members around the governance of the King's Office.
She confirmed that at the iwi chairs dinner, comments were made about leadership that were referring to Mr Morgan, but she did not hear his name being used.
Former directors of the Ururangi Trust, Traci Houpapa and Sir John Goulter were mentioned in the letter as losing their jobs as a result of Mr Whakaruru.
Sir John said these are ongoing issues and he is not completely surprised by them.
However, he said the publicity is not good for Tainui and the Kiingitanga.
Traci Houpapa said she is a strong supporter of the Kiingitanga and is not concerned about how she left her role as Director.
The Serious Fraud Office said it became aware of the letter today and would be interested in seeing the details in it.
However, it would not comment on whether those details could be used as part of its current investigation.
The annual Koroneihana celebrations are due to kick off in Ngaruawahia on Friday.