Misguided or paranoid - Act leader David Seymour says those opposed to the TPP are one or the other.

He says the Treaty of Waitangi was the original Pacific trade agreement and the Trans-Pacific Partnership won't undermine it at all.

John Key was heckled over the deal at Ratana yesterday.

Opponents say the secrecy of the deal undermines the spirit of the Treaty - a point likely to be raised again at Waitangi Day commemorations in a fortnight.

But David Seymour said most opponents are either misguided about the impact of the deal or paranoid about its potential effects.

"Their fears will be allayed once they realise they can import their own tinfoil hats under the TPP."

Seymour said the deal won't undermine the Treaty of Waitangi or sovereignty, and will give New Zealand the best of both worlds, "being both independent and sovereign, and giving access to much larger markets."

The Prime Minister said he thinks concerns stem from misinformation.

"Since 2011 I think there has always been a recognition of free trade agreements about the importance and the preeminence of the Treaty of Waitangi."

"So when we went into the TPP negotiations we said look, that boundary can't be crossed."

That view is at odds with those expressed by Ngapuhi leader Kingi Taurua, who threatened to block the Government from Te Tii Marae on Waitangi Day if the Trans Pacific Partnership is signed.

He said Maori had protested the secrecy of the TPP negotiations and many had filed claims with the Waitangi Tribunal alleging the deal was a breach of the Treaty of Waitangi.

"For me, the first and most important thing is the Treaty. I believe [the TPP] is a breach of the document. Maori have been left out, the Treaty was a partnership between two people but it appears we have been left out."

The potential for sovereignty to be undermined was also a concern for the Sustainability Council, who say the government could be sued if they pass laws that affect corporate interests operating within New Zealand.

Executive director Simon Terry said once the agreement is signed, any laws the government makes to protect our environment, could be seen to be getting in the way of an investor's future profits.

"The government could lose interest in making that reform, and so it's the environment that would ultimately pay the price, even though the taxpayer would fork out if the company is successful in suing the government."