The Australian dairy industry has expressed "extreme disappointment" over what it calls a back-flip by the United States in negotiations over a major regional trade deal.

According to industry figures currently in Maui, Hawaii, for talks on the Trans Pacific Partnership Agreement (TPP), the US is not sticking to a position agreed to 18 months ago which was to be the starting point for this round of negotiations.

"When we heard, we were absolutely devastated by it because it put us back so much," Australian Dairy Council chairman Noel Campbell said.

"We thought 18 months ago we had moved a long way, and not to understand it was changing right at the last minute was really distressing."

Australian dairy farmers are seeking better access to the US market as part of talks around what could possibly become a major trade and investment agreement for the Pacific Rim.

The industry is looking for access into a huge consumer market currently subject to a regime of quotas and tariffs.

But the industry also expects the US, which initiated the TPP, to take the lead in breaking down trade barriers.

According to Mr Campbell the US now will not budge unless Canada opens its markets.

Meanwhile US officials have said they do not believe the previous position with Australia "had been agreed to".

"We were totally surprised. It came out of left field. The government — exactly the same," Mr Campbell said.

The week-long discussions are supposed to close this weekend and are considered one of the final chances to seal an in-principle agreement before upcoming elections in the US and Canada.

"So when you've got a very short time to negotiate these sorts of things it's absolutely what you don't need," Mr Campbell said.

"I guess it's always going to be an issue with the Canadians in dairy with how they operate in dairy and other things so it's not unexpected but certainly the US thing is unexpected."

First trade talks since US senate handed power to president

The talks are the first since the US senate gave the president the power to negotiate trade agreements such as the TPP without them being picked apart later by lawmakers.

The deal is meant to be one of Barack Obama's signature policies to strengthen US economic ties and presence in the Asia Pacific region.

There are 12 nations involved in the negotiations, including Japan.

On that front, Australian dairy farmers could have reason to feel more confident.

"With respect to some of the other markets, it's moved more substantially and we believe we'll be able to have a deal with Japan, which is one of our major markets, which is superior to what we've currently got under the Economic Partnership we had with Japan last year," Mr Campbell, who is also the president of the Australian Dairy Farmers Association, said.

He said the changed US position could not be accepted and had undermined confidence in the proceedings.

He also said Trade Minister Andrew Robb and the negotiating team had done a good job and would take the dairy industry's position significantly into account.

Mr Robb said dairy remained an important consideration and the Government was "continuing to push for meaningful gains in both the US and with other TPP countries".