UPDATED 5.45pm: Another big concession has been revealed in Trans-Pacific Partnership negotiations.

University of Auckland Law Professor and anti-TPP activist Jane Kelsey says the US has included a chapter on state-owned enterprises.

She believes it puts sweeping restrictions on governments preventing them from subsidising or providing guarantees to state-owned enterprises, if that adversely affects ‘another country’s interests’.

"It will be really hard to reestablish new SOEs that require government money to go in them, for example, Labour's proposed Kiwi-Assure state-owned enterprise that can fill the gap that the private sector doesn't fill."

Other concerns have been raised over what rights New Zealand will have to restrict foreign ownership of local property under the Trans Pacific partnership free trade deal.

Winston Peters says one of the consequences of the deal will be that Parliament won't be able to impose a ban on land sales to citizens of TPP signatory nations.

The Prime Minister's not ruling out the fact the trade deal may prevent the Government from imposing a ban on the sale of Kiwi land to foreigners.

He's made it clear his Government wouldn't support such bans anyway, and that has Winston Peters up in arms.

"Is he happy to go down in history as the leader who did his best to hand over the powers and rights of this parliament to foreign governments and to put the welcome foreign buyers sign up for kiwi land and homes?"

John Key said he wouldn't want to say whether or not the trade deal may have implications  today because the TPP hasn't been concluded.

"There may be implications in terms of bans but as the government said and as I said during the week, we don't favour a ban on sale of residential property or land. We think there are far better ways of addressing that."