United Future leader Peter Dunne has derided pamphlets being distributed in his Wellington electorate as "disgraceful, despicable racist bigotry".
The Ōhāriu MP said he has been contacted by several constituents this week offended about flyers bearing the slogan "One Treaty, One Nation".
Wellington publisher John McLean is behind the flyers, which call for an "end to the stranglehold that one minority group has over the culture and life of the nation".
Hundreds of thousands of the pamphlets have been dropped in mailboxes across the North Island over the past few months, Mr McLean said.
They also call for the Waitangi Tribunal to be abolished and say Māori have benefited from colonisation, lifting them out of "a violent, Stone Age existence".
Mr Dunne has encouraged people to throw the flyers in the "time-honoured order of the bin".
"The perpetrators of this sort of vile rubbish need to get a clear message that their bigotry is not acceptable in an open society.
"Ōhāriu is a vibrantly multicultural electorate, and the views expressed in these leaflets stand in stark opposition to the values I have had continually expressed to me by the people of this diverse, open and tolerant electorate."
'What is racist about calling for equality?' - McLean
Mr McLean said Mr Dunne's comments were in "the long tradition of smearing your opponents when you run out of arguments".
"We've reached a pretty bad point when an MP labels as racist those who are calling for a single standard of citizenship for all New Zealanders.
"To describe this as racist is a contradiction of terms... what is racist about calling for equality before the law for all citizens?"
The pamphlet states contributions can be made to a campaign called "Rolling Thunder" which is connected to the now-deregistered political party, 1Law4All.
It also promotes the book, One Treaty, One Nation, published by Mr McLean, which includes a chapter by former National and ACT leader Don Brash.