Ngāpuhi kaumatua Kingi Taurua has told iwi leaders to "wake up" as the tribe argues whether to let the Prime Minister on to Waitangi's lower Marae later this week.
Northland iwi leaders are today meeting to decide whether they will block Mr Key from Waitangi's Te Tii Marae grounds on Friday.
Mr Taurua has told the hui that John Key is breaking the law by signing the Trans-Pacific Partnership (TPP) and that coming to the Marae, just days after signing the agreement, is "rubbing the salt in".
"I don't understand why we want to welcome a Prime Minister when he has already signed away our sovereignty," he said.
Labour MP Kelvin Davis, former MP Dover Samuels and others are also gathered at Te Tii Marae for the meeting.
Regardless of the decision, Mr Key says he isn't fazed by protests or threats to ban him at Waitangi.
Mr Key says he will respect the elders' decision but is not put off attending.
"When I was leader of the Opposition I criticised Helen Clark for not going, and I said 'Well, if I become Prime Minister I'll go'," he told the Paul Henry programme this morning.
"Unless they reverse their decision and say 'don't come', we'll be coming - protests are not new at Waitangi, every single year I go there there's something."
Mr Key first attended Waitangi as leader of the Opposition in 2007, and as Prime Minister in 2009.
Discussion of why the trade deal was important for the country would be top of the agenda when he met with iwi leaders.
"I'm more than happy to go and have discussions about why TPP is good, I'm not in the slightest worried about that.
"It's a $40 billion economy. If you want me to make it more difficult to sell your things to America and easier for Australia then don't sign."
The TPP is set to be signed in New Zealand on February 4.