Mike Petersen, New Zealand's envoy for agricultural trade says farmers could put their trust in negotiators.

Experts claim Waikato's dairy sector will be guaranteed a fair deal before New Zealand's negotiators lock in a Trans-Pacific Partnership (TPP), though industry leaders continue to voice reservations.

Failed negotiations in Hawaii earlier this month prompted concerns from some dairy industry leaders that our exports would be no better off.

Thousands around the country will take to the streets on Saturday to protest against the agreement, although economists and industry leaders have assured naysayers "we're not selling New Zealand up the creek".

Former chairman of Beef and Lamb New Zealand, Mike Petersen said the current deal on the table for dairy was not good enough, but said our negotiators would not fail farmers.

"I know it's really hard to understand this, but we need to put some faith in our negotiators. They are the best negotiators in the country."

Petersen, New Zealand's special envoy for agricultural trade, was at the talks in Hawaii and said the deal was "98 per cent done".

"The agreement would need to see much more in the dairy deal to make it something dairy can accept.

Aside from dairy, auto and intellectual property were the other final things left to nail down, he said.

"I've seen all the comments saying it will mean New Zealand is selling its sovereignty, but I can assure you that's not the case. We're not selling New Zealand up the creek."

Concerns the dairy sector may face limited market access to America, Canada and Japan were raised by Federated Farmers dairy spokesman Andrew Hoggard.

"Until the Americans, Canadians and Japanese get it into their heads that a free trade deal is actually about free trade ... we might be at loggerheads," he said.

Hoggard said our negotiators needed to continue playing hard ball "until we've got a real free trade agreement".

"If we get a free trade deal that's actually a free trade deal, that would be huge.

University of Waikato economics Professor Frank Scrimgeour was confident the agreement would increase New Zealand's trading opportunities.

"For 30-40 years we've gradually been trying to reduce trade barriers around the world. Everything which reduces those barriers increases the price that we get for our product and increases the volume that's sold."

Scrimgeour said his experience in economic studies pushed him to be a strong supporter of the TPP.

"But there are always potential little fishhooks in the details and it's important to get those right."

For sheep and beef exports, the existing deal was good, said Beef+Lamb NZ market access general manager, Ben O'Brien.

O'Brien said New Zealand had been lobbied alongside other beef exporters in the Five Nations Beef Alliance - the US, Mexico, Canada, Australia.

"We have stuck together on that to ensure so we'll expect to all get the same deal."

Our exporters could lose out if New Zealand was not part of the agreement, he said.

"If New Zealand says, 'We're not going to sign TPP', we'll be up against Canada, the US and Australia who would then have preferential access to other markets that we wouldn't have access to, so we would immediately be at a significant disadvantage."

Beef+Lamb chairman James Parsons said New Zealand could face being squeezed out of the market if it lost that access.

The possibility of paying more for pharmacy prescriptions and over-the-counter medicine remains unclear.

The way the Government spent the health budget was the primary concern for the Pharmacy Guild, said chief executive Lee Hohaia.

Hohaia said companies already struggled to get more expensive medicine subsidised.

"We would hope that access to such medicine would be improved rather than reduced."

New Zealand is negotiating the TPP with the United States, Australia, Brunei Darussalam, Canada, Chile, Japan, Malaysia, Mexico, Peru, Singapore, and Vietnam.