Health organisations and medical experts are warning Maori could be put off buying medicines if the Government signs the Trans Pacific Partnership agreement.
A forensic psychiatrist said the agreement would protect the intellectual property rights of the pharmaceutical industry and make medicines more expensive.
Erik Monasterio said if the Government agency Pharmac was unable to buy generic medicines as quickly due to legal concerns, their cost was likely to remain higher for longer.
Dr Monasterio said many Maori have lower socio-economic status and a higher incidence of chronic illnesses, both physical and mental.
He said if the price of medicines went up and people had to pay higher part charges for their prescriptions, Maori would be deterred from using them and their health might suffer.
Govt rejects claim of TPP harm
But the Minister of Trade Tim Groser says the Government will not support anything in the TPP that would dismantle the Pharmac model or undermine its ability to continue delivering cost-effective health outcomes.
Mr Groser said officials from the ministries of Health and Foreign Affairs and Trade continued to work closely to ensure the Government's right to regulate in the interest of public health, and the fundamentals of the New Zealand health system, were protected in the TPP.
He said there had been a proactive consultation process and regular meetings with a wide range of stakeholders, including health sector representatives.