Japan was an important market for New Zealand, she said.
"It is heavily protected in the agriculture area. TPP membership is going to be extremely good news for New Zealand agricultural exporters."
NZIER deputy chief executive John Ballingall said a full liberalisation type agreement could be worth hundreds of millions of dollars a year to New Zealand, and more if Japan was included.
"At the moment there's not a lot else happening on the trade liberalisation front, the TPP is where all the momentum is and at a time when Doha [World Trade Organisation talks] is struggling to say the least, it's really encouraging that there are at least some areas where regional economic integration is progressing," Ballingall said.
"Our export sector has really pulled us through this recession and so we've seen the benefits that come from having a thriving export sector and if TPP can help us improve our export sector further then that's likely to deliver wider benefits to the economy."
The announcement around Japan was highly significant, Ballingall said.
"It means that we've now got two of the world's superpowers, one in and one considering the agreement and that should just help it generate momentum and it will mean that other large economies like Korea, possibly China, will start looking at it and thinking, 'Well if Japan wants in then perhaps we do as well'."
Federated Farmers said a TPP would be transformational for New Zealand agriculture and the economy by involving five of the country's top 10 export partners, including three of the top four.
Federated Farmers president Bruce Wills said a TPP could boost exports to the United States enormously "and it's only one partner".
The crucial thing for Federated Farmers was the removal of trade barriers for agriculture, Wills said.
"That's a non-negotiable requirement for us as the world needs to eliminate tariffs and subsidies," he said. "Free trade also needs a wider genuine commitment to services, investment and intellectual property."
ANZ chief economist Cameron Bagrie said the developments around the TPP were encouraging, especially Japan's move to rejoin talks, although political challenges would be likely as the negotiations continued.
"Of course what we know is the negotiating and settling of these agreements do tend to be reasonably long and drawn out processes," Bagrie said.
But he said agreements like the TPP were crucial for this country's future.
"If there's one dynamic I think New Zealanders are seriously under-estimating it is how important, strategically, these bilateral trade agreements ... are going to be to this economy five to 10 years out." Bagrie said.
He said the events taking place in the debt-ravaged eurozone highlighted the importance of countries working together in "group orientated leadership", rather than "self-interest orientated leadership".
Top prospects
Trans-Pacific Partnership:
* Aims to create a regional free trade agreement between Australia, Brunei, Chile, Peru, Singapore, the United States, Vietnam and New Zealand.
* Japan has also rejoined talks.
* Member countries, excluding Japan, are home to more than 500 million people, with economies accounting for US$17.8 trillion, or just over half, of Apec's gross domestic product.
* The TPP would include four of New Zealand's 10 most important trading partners.
Source: Ministry of Foreign Affairs and Trade (MFAT)
- additional reporting AP
