"She also supervised the invasion of Maori communities in Taneatua and Ruatoki in the false belief that terrorism was rife.
"However, that has since proven to be a wild made-up dream. She as yet hasn't acknowledged these mistakes so, as a matter of principle, we cannot support her nomination," he said.
Mr Flavell said it wasn't about an apology, it was about a candidate for the world's top diplomatic posting displaying that she had the necessary respect and understanding of indigenous communities.
"We simply can't pretend history didn't happen," he said.
"We all make mistakes but if she has learnt from hers and is prepared to acknowledge them, we would review our position," he said.
But Mr Maxwell said the past should be put aside.
"For me I am very disappointed in the direction of the Maori Party not supporting Helen Clark. I think you should put all other things aside and think of what is best for New Zealand. I saw Helen's debate on TV and watched the whole lot and I was so proud of her and I think she has a good chance.
"Regardless whether it is Helen Clark or Jim Bolger, you get behind your people. We are only a goldfish in a big pond. She has got a good chance and I hope this doesn't jeopardise it in any way."