Public health advocates and business groups are concerned that pharmaceutical giants will be able to advance their commercial interests in the once-in-a-lifetime pact through their seat at the negotiating table, while the details are kept secret from the Australian public.

Some of the measures that Pharmaceutical Research and Manufacturers of America (PhRMA) has publicly lobbied to be included in the Trans Pacific Partnership have subsequently appeared in draft versions of the agreement that have been leaked by Wikileaks.

These include 12 years of data protection - which would restrict the use of clinical trial data to register competing products - extended patent protections and allowing patents to be granted on minor variations to existing drugs.

Public Health Association spokeswoman Deborah Gleeson said the negotiating text should be made available to everybody, as it was for other trade pacts such as the World Trade Organisation drafts and anti-counterfeiting agreement.

"US corporations have a much higher level of access to what's going on in the negotiations and to the text itself, whereas health and community organisations are reliant on the leaked drafts for information," Dr Gleeson said.

"Public Health Association has had briefings from DFAT but you don't learn very much about what's being discussed. They often give us information about Australia's position in the negotiations but they often can't discuss the detail about what's actually being proposed."

Provisions in draft versions of the TPP, such as secondary patenting and extended data protection, were antithetical to the affordability of medicines, she said.

The 2013 Pharmaceutical Patents Review recommended that a five-year extension on patent terms that was locked in under the Australian-US Free Trade Agreement should be reduced as it had not resulted in more research and development in the pharmaceutical industry and was not in Australia's interests.

It had cost the Pharmaceutical Benefits Scheme $240 million in 2012-13 and would cost $480 million in the long term.

PhRMA is a member on one of 16 industry trade advisory committees to the United States that are designed to "engage business leaders in formulating US trade policy" and gives them access to classified trade information.

Other advisory committee members include Johnson & Johnson, the Biotechnology Industry Association, Yahoo! Inc, Apple Inc, Halliburton, Chevron and Eli Lilly, a drug company that sued Canada for strengthening its patent laws.

The Australian Chamber of Commerce has also attacked the secrecy surrounding the TPP and has asked the federal government to give certain pre-registered bodies confidential access to the draft text of Commonwealth treaties, as they are in the United States.

In a submission to the federal government last month it said these groups should be given continuing access to the text as it evolved.

Eight health and community organisations wrote to Trade Minister Andrew Robb on Monday with concerns about the TPP.

The latest draft leaked by Wikileaks in March included a mechanism for foreign corporations to sue governments over their health and environmental policies, and although Australia was exempted from the provision a further footnote indicated this was "subject to certain conditions" which were not specified.

Mr Robb said there had been more than 150 consultations with stakeholders interested in health-related issues since 2011 and 50 consultations in the past 12 months alone.

"These consultations have been extensive and have proved invaluable in terms of guiding our approach to the negotiations," he said.

The 12 negotiating parties to the TPP had agreed to keep negotiating documents confidential and any earlier release would have to be with their agreement.

Australia did not support positions that would result in higher cost medicines or which would adversely impact on Australia's health system more broadly, Mr Robb said.