Environmental consultant Nelson Lebo told the gathering there was a widening gap between the rich and poor.
"Given corporations' policies of making a profit for their shareholders and the government's lack of strong regulations, can we really trust a secret agreement driven by corporate interests?"
Ms Roberts shared her concern that under the TPPA medicines could become more expensive and Pharmac would become a barrier to profit-making by the drug companies.
There were also concerns around downloading movies and music on the internet.
"Our environmental laws and the Treaty of Waitangi will all potentially be overridden by corporate interests."
Auckland University law Professor Jane Kelsey wrote from Singapore that there was strong disagreement during the meeting of the 12 ministers who were negotiating the TPPA.
The free trade TPPA involves 10 Asia/Pacific Rim countries.
Ms Kelsey said the disagreement was around whether a deal could be struck without the US President having fast-track authority, known as the Trade Promotion Authority (TPA).
"No Fast Track means the Congress can pick the deal apart, keeping the bits favourable to US interests, rejecting concessions they don't like, and demanding that TPPA countries give more."
Ms Kelsey continued that there was so much disagreement among ministers that journalists at the negotiations were asking how they could contemplate making decisions within the week, let alone starting trade-offs.
"Several weeks ago John Key conceded that Obama might not get fast track or even be able to get a final deal through Congress, but nevertheless urges an early conclusion to the deal," Ms Kelsey said.