The government has refused the Senate access to the secret text of the trade deal it is negotiating in Singapore, saying it will only be made public after it has been signed.

As the final round of ministerial talks on the Trans-Pacific Partnership resumed on Sunday, Nobel prize-winning economist Joseph Stiglitz wrote to each of the 12 participating nations warning that the deal and the secrecy surrounding it presented ''grave risks''.

Trade deal: Australian Trade Minister Andrew Robb, left, with his Korean counterpart, He Yoon Sang-jick. Credit:DFAT

Australia's delegate, Trade Minister Andrew Robb, has told Fairfax Media he is prepared to agree to so-called ''investor-state dispute settlement provisions'' in return for access to markets including those of the US, Japan and Canada.