The head of the New Zealand International Business Forum is confident of progress on agriculture tariffs in the Trans Pacific Partnership.
About 500 officials from 11 participating countries launched the 15th round of talks for the Trans Pacific Partnership in Auckland on Monday.
Prime Minister John Key has said New Zealand won't sign up to the deal unless it includes an agreement to abolish tariffs on agricultural products exported to the United States.
Business forum chair Sir Graeme Harrison says the US has recognised opportunities in the Asia-Pacific region for greater trade access, but it may take 10 to 15 years for tariffs to go.
Sir Graeme - who is the founder of one of New Zealand's biggest exporters Anzco Foods - says agriculture would be the biggest winner from the 11-country trade deal.
"I'm more confident that I've ever been that we can in fact achieve a comprehensive agreement with the United States. The point will be how long to phase out restrictions. So we could be in for a period of 10 to 15 years in which tariffs will be phased ... quotas disappear."
Sir Graeme Harrison says he and other business leaders signed an open letter supporting the talks because they wanted to highlight how important trade and foreign investment are to the economy.
Council of Trade Unions' economist Bill Rosenberg says strong lobby groups in America want to protect the agriculture sector.
Mr Rosenberg says the latest talks also touch on contentious issues of intellectual property rights and state subsidies and he is uneasy at secrecy surrounding the negotiations.
He says there should be more transparency, as citizens would normally expect to be able to vote on such subjects in an election.
