Maori Party co-leader Tariana Turia says some Maori Party supporters in Northland have received threats from supporters of Hone Harawira's Mana Party since it decided to stand a candidate against him.
Ms Turia said the Maori Party had suggested the recipients of the threats to take the matter to the police, saying it was intolerable for intimidation to be used.
However, Mana leader Hone Harawira said he did not know of any threats being made and in the absence of any evidence, it remained speculation and innuendo.
"This is pure speculation. She hasn't named anybody, she just laid down some innuendo and every single one of you seems to have picked up on it. If you don't mind that's not something I wish to continue."
Mrs Turia said the threats related to their participation in the Maori Party.
"It's not acceptable. These people have been threatened in the vicinity of their own places, which I think is appalling."
Asked if they were threats of violence, she said "I think if you're threatened, I would take to mean it could be physical, it could be anything."
Mr Harawira said if threats were made by either side to the other, he would not condone it.
"I do not think that's where we want to be going with this by-election."
If threats had been made, Mrs Turia knew who the appropriate authorities were.
"I think Tariana Turia has been around long enough to know that if she feels threatened, she can take it up with the appropriate authorities."
The alleged threats are understood to have been made in an email and in person at the home of a Maori Party supporter who attended the hui held by the Maori Party at Te Tii marae on Saturday.
The accusations will heighten an already contentious by-election. Both the Maori Party and Labour have now decided to stand candidates against Mr Harawira in the Te Tai Tokerau seat.
Mrs Turia has also raised concerns about the way the party's MPs were treated by Mr Harawira's mother Titewhai Harawira at a hui on Saturday. Mrs Harawira reportedly called Mrs Turia a 'snake,' a 'liar' and said the co-leaders were swinging from Prime Minister John Key's jockstrap.
Mrs Turia said people's names were written down and they were told "if they showed their faces in Kaitaia, they'd know all about it."
Mr Harawira is expected to resign his seat this week to force the byelection, saying he needs a new mandate from the Te Tai Tokerau voters to represent them as Mana Party leader.
Labour's Phil Goff confirmed today that Kelvin Davis will stand against Mr Harawira. The Maori Party is waiting for the by-election to be called before it selects its candidate, although several high profile names have been proposed.