The US has called a meeting of ministers from Australia and the 11 other nations negotiating the Trans-Pacific Partnership (TPP) in a bid to finish the trade deal, a key part of the US administration's engagement with Asia.

The pact seeks to cut trade barriers and set common standards for 40 per cent of the world economy and will be a legacy-defining achievement for US president Barack Obama.

The US Trade Representative said in a statement that ministers would meet in Atlanta from September 30 to October 1.

The ministerial meeting will be preceded by a meeting of chief negotiators from countries including Australia, New Zealand, Chile, Malaysia and Brunei from September 26 to 29.

"Trade ministers and negotiators last met in July and have been making good progress toward resolving the limited number of outstanding issues," USTR said in a statement.

The last ministerial talks, in Hawaii, stumbled over dairy trade, monopoly periods for next-generation, biologic drugs and rules of origin for autos.

Officials close to the negotiations said on Wednesday that two days of talks on the threshold for local content in auto trade between the United States, Canada, Japan and Mexico had made progress, and they aimed to reach a final deal next week.

Mexico and Canada, US partners in the 20-year-old North American Free Trade Agreement, have built automotive supply chains based on a threshold of 62.5 per cent local content, and objected to having a much lower threshold in the TPP, which they feared would favour Asian auto parts makers such as Thailand.

Another sticking point is how long to protect data used to develop biologic drugs.

Washington is pushing for 12 years' protection, much longer than the current protection periods in countries including Australia, New Zealand and Chile.

Chile's head of international trade said that although conditions were now present to finalise the TPP, talks would likely still go down to the wire.

"You never know until the last minute if it is possible to find a balance or not," Andres Rebolledo said in a telephone interview.

Major dairy exporter New Zealand has made it clear it will only sign up to a deal which expands market access, putting pressure on the United States and Canada — in the midst of an election campaign — to allow more dairy imports.

"Canada continues to have robust discussions with our negotiating partners and stakeholders on a range of issues. Discussions have been positive, but difficult issues remain," a spokesman for Canadian trade minister Ed Fast said.

Reuters