New Zealand Prime Minister John Key says there's a chance the Trans-Pacific Partnership trade deal could be completed this week.

Trade ministers from the 12 Pacific Rim nations, including Australia, New Zealand, Canada and the US, are meeting in Atlanta in an attempt to hash out what would become the largest trade zone deal in history.

Key was upbeat about the negotiations, but added the window for sealing an agreement this year was closing.

"Personally, I still think TPP can take place," Key, speaking at the Asia Society in New York on Wednesday at an event hosted by former Australian Prime Minister Kevin Rudd, said.

"I think there's actually a chance it could get completed this week.

"There's significant negotiations being undertaken in Atlanta.

"The window of opportunity to complete the TPP is closing, so you wouldn't say it's impossible to complete the deal if it doesn't take place in Atlanta, but it does become more difficult."

He said the last opportunity for 2015 could be when APEC is hosted in the Philippines because beyond that the US election cycle kicks in with primaries.

Key said he has mixed views on China's economy.

"Our view on China in terms of what we see, there's clearly some distress within the Chinese market, but the consumer demand side is still strong," Key said.

The wide-ranging discussion with Rudd also touched on New Zealand's new flag, the extradition proceedings of Kim Dotcom and a bet involving the Rugby World Cup.