Trade Minister Tim Groser will only attend Trans-Pacific Partnership (TPPA) talks if progress is made on dairy market access, saying the deal in its current form is "inadequate".

Negotiations on the 12-nation trade pact had stalled, but negotiators would meet in Atlanta, in the United States, on September 26 to discuss outstanding issues.

The United States has called for ministers to meet after that, amid reports progress had been made on automobile market access.

But Groser said his strong view was that there was no point in getting ministers together unless there had been progress on all the underlying issues.

Market access for dairy and patent extensions for pharmaceuticals were the other remaining areas for negotiation.

Should negotiators make "sufficient progress", including on dairy market access, Groser said he intended to travel to Atlanta to meet other trade ministers.

"We think there is an excellent deal on everything other than dairy, and on dairy, it is just not adequate - that's the simplest way to describe it.

The dairy deal "doesn't meet any definition that we could agree on for commercially meaningful access - but that's not a precise thing...it can only be defined through the negotiating process."

Groser emphasised that nothing was agreed until everything was agreed, and other things could still be taken off the table.

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Prime Minister John Key on Monday said the deal was "a long way from being in the best place we could be on dairy".

The end deal would "hopefully land in the right place," but would be "the very best we can do," Key said.

The Government's previous stance was that New Zealand would not sign the TPPA if the dairy deal was not a good one.

Auckland University law professor Jane Kelsey, a prominent critic of the TPPA, said "no noise" about dairy lent support to her view that automobile trade protectionism was the big issue "and once that is settled dairy is not expected to delay a final agreement".

"Put another way, Groser is expected to swallow the rat, rather than hold up the deal, and wear the flack at home by saying New Zealand couldn't afford not to be part of the TPPA," Kelsey said.

The Government has negotiated the deal in secret, drawing criticism from those who want to see the text before it is signed.