UPDATED 4:22pm: Public welfare moves made by Governments look set to be largely protected from corporate legal challenge in the proposed Trans Pacific Partnership free trade deal.

Leaked papers from Wikilieaks confirm controversial investor state dispute mechanisms are part of the Trans Pacific Partnership free trade talks.

Clauses in the document show there are provisions covering cases where companies could take legal action against Government's of actions that are seen to damage their business interests.

They contain specific procedures for mediation and tribunal arbitrations and would require any disputes to be settled according to international law and conventions.

Tribunal rulings could see orders made towards the awarding of monetary damages and restitution of property.

Opponents of the deal argue it could allow corporates to sue governments when law changes harm their business.

However a clause in the released document says non-discriminatory regulatory actions for legitimate public welfare objectives are not indirect expropriations, except in rare circumstances.

The Government's saying little so far about the release.

Deputy Prime Minister Bill English says he's unaware of what's been leaked so he can't really comment on it.

"I can't comment on the chapter but it's not a new issue. There's always been investor state disputes as part of free trade agreements so I'd have to look at the chapter before I could comment."

The Green Party is crying foul over latest details.

Green MP James Shaw says it shows the deal is preparing to go further than other FTAs in allowing foreign companies to sue Governments.

"What it seems is, is that this chapter does go a lot further than the provisions that are provided for, either under the Korea agreement that we signed yesterday or the China agreement that we signed a few years ago."