At a public forum organised by critics of the Trans-Pacific Partnership on Thursday, Médecins Sans Frontières Australia's advocacy manager Jon Edwards said leaked chapters showed it granted pharmaceutical companies extended patents, allowing them to charge higher prices.

The regional trade pact, which involves 12 countries covering 40 per cent of the world's economy, has also come under fire for containing a clause that allows multinationals to sue governments if new laws harm their profits.

A late-stage draft of the Investment chapter, leaked in March by Wikileaks, showed some public health carve-outs, specifically the Pharmaceutical Benefits Scheme, Medicare Benefits Scheme, Therapeutic Goods Administration and the Office of the Gene Technology Regulator.

But Mr Edwards told a crowd of more than a hundred at NSW Parliament House that these exemptions were "seriously flawed".

"MSF is not convinced that they will protect countries like Australia, let alone Vietnam, Malaysia or Peru, from the threat of pharmaceutical companies exercising legal threats or action to enforce monopolies they are afforded in the TPP," he said.

Patricia Ranald, co-ordinator of the Australian Fair Trade and Investment Network (AFTINET), who organised the forum, said the carve-outs showed the government's assurances about general safeguards embedded in the TPP did not hold water.

"The fact they've named those specific institutions means that the general safeguards are not effective. If we have to name those institutions, how about the other ones such as in food regulation, environmental protections?"

Trade Minister Andrew Robb refused to answer questions about the exemptions, saying he would not engage in debates over "leaked, outdated documents". He said the only text that mattered was the final text.

On Thursday, the Australian Council of Trade Unions joined counterparts from the 12 negotiating countries in calling for trade talks to cease unless they were conducted with "genuine, transparent, public mandates that place people front and centre, not big corporations".

It criticised the government for conducting the negotiations in secret.

Additionally it raised concerns about indications in leaks that some countries are attempting to reject protections of workers' rights and that the deal will not cover the United Nations International Labour Organisation conventions on rights at work.

"The TPP makes corporate profits more important than protections for clean air, clean water, climate stability and workers' rights," said ACTU president Ged Kearney. "A fair trade deal needs to recognise and protect workers' rights, environmental standards and access to quality public services – this is not happening with the TPP."

Mr Robb described the call as the latest round of scaremongering by anti-trade groups. He said the ACTU had taken part in 14 separate consultations on labour issues.

"It beggars belief the ACTU is opposing efforts to create jobs for Australians. By criticising the approach to TPP labour chapter negotiations, they are criticising themselves given they have been actively involved in guiding this approach," he said.

Mr Robb questioned whether Ms Ranald was being up front about her links with trade unions.

At the forum, Ms Ranald said AFTINET represented church, union, public health, environmental, and women's groups, amongst many others.

"I don't think being accused, being associated with unions is such a crime. We're diverse," she said to loud applause.

Mr Edwards said MSF was far from anti-trade.

"MSF is not anti-trade, quite the opposite. MSF is pro-trade and pro-competition in the pharmaceutical business, where it can reduce prices and bring benefits to our patients and others in need of essential medicines," he said.