"Apparently, they [National and the Maori Party] have been acting like they are very good friends and this friendship is tipped to blossom into a full-blown partnership.
''What a mix.
''Merchant bankers and Maori separatists.
"One lot will be trying to sell the country out from under us - while the other will be setting up a separate state."
National had never recanted its policies of the 1990s and the Maori Party was committed to separate development, he said in a speech prepared for the launch of the NZ First election campaign in Auckland.
Mr Key led the questioning in the House whether Mr Peters should stay as Minister of Foreign Affairs.
Even though he has stood aside from the role, he continues to receive the benefits and pay from being a minister.
The National Party leader also ruled out any deal with Mr Peters after the election, gambling that he could form a government with the help of the Maori Party, Act New Zealand and United Future.
Mr Peters and Maori Party MPs clashed in Parliament in the last sitting week, with Maori Party leader Pita Sharples claiming he had been pressured to have the party vote against Mr Peters being censured by the privileges committee for not declaring a $100,000 donation from wealthy businessman Owen Glenn.
Mr Peters did not hold back from his criticism of Mr Key, who he described as being heavily promoted by the foreign-owned media and his friends among the finance barons waiting to loot New Zealand's remaining assets.
"For these overseas interests, people voting in a general election are an inconvenience."
NZ First would wait until the votes were counted and it worked with whoever voters told it to, he said.
"We are not saying who we will go with, or won't go with.
''We will do as you say.
''And we will not allow the process to be subverted."
Mr Peters' only option to return to government, if Mr Key keeps his word, is with Labour and the NZ First leader kept his criticism of his protector to a minimum. However, Mr Key may have to do some serious back-pedalling if he needs the Maori Party to form a National-led government.
Maori Party co-leader Tariana Turia made it clear at her party's launch on Saturday that the entrenchment of the Maori seats in Parliament would be a bottom-line for her party.
National would have to abandon its plans to phase the seats out from 2010 if it wanted to work with the Maori Party after the election.
"I think the interesting thing will be if we get into a negotiation with National and if they agree to entrench.
''They'll have to if they want to work with us.
"Then I think we'll see where Labour really sits.
''Because if National gets in and then the vote goes into the House and Labour votes against it, that will send the strongest message to our people."
Dr Sharples said Maori might not get too many more chances to have their voices heard in Parliament.
Maori people had twice looked away from Labour in recent years - to NZ First in 1996 and to Alliance partner Mana Motuhake in 1999 - and they had twice been failed.
"I think it's really vital that our people realise that if not this time, then over the next three years, that this is an opportunity that has to be taken now.
''Otherwise it's gone."
The Maori Party has four MPs and is aiming for at least six from the seven Maori electorates after the November 8 election.
It also wants to lift its party vote from the 2.12% it received in 2005.
The Green Party launch concentrated on the future of the country and being the voice of the 900,000 young people and children who could not vote in the election.
Co-leader Russel Norman did find common ground with Mr Peters when he criticised both Labour and National for failing to go public about poisoned baby food manufactured in China by a subsidiary of New Zealand dairy giant Fonterra.