Labour's new leader wants the government to release details of the Trans-Pacific Partnership (TPP) negotiations but Prime Minister John Key won't do it.
David Cunliffe says there are problems with the free trade deal being negotiated by most Asian countries, the United States, Australia and New Zealand.
"There are some real fish hooks in it," he said on Monday at his first press conference in parliament since being elected on Sunday.
"One is investor state relations, another is Pharmac, another is intellectual property rules, and another is the degree and rate of upside in our agricultural opportunities."
Mr Cunliffe says the TPP is going to be a difficult and complex issue for New Zealand and the government should reveal details of its negotiating stance.
"My challenge to John Key and his government is to put that information in the public domain so the debate can begin."
Mr Key says he's not going to do that.
"We're trying to complete a deal and it's very, very important for New Zealand," he said.
"It would be worth billions of dollars and thousands of jobs."
The TPP negotiations, scheduled to be concluded next year, began in 2010 and are in their 19th round.
Opponents, including trade unions, fear New Zealand's interests will be compromised but Mr Key says he won't sign anything that isn't good for the country.