Labour leader Andrew Little says the party is prepared to flout parts of the Trans-Pacific Partnership trade deal if it becomes Government.

A Labour-led government would "scrap out" issues, like its plan to ban foreign house buyers, with other countries in the Trans-Pacific Partnership Agreement (TPPA) free trade deal, Labour leader Andrew Little says.

Labour remained committed to introducing laws to restrict the sale of houses to non-resident foreign buyers, Little said after Prime Minister John Key confirmed that would not be possible under the 12-country deal.

"If it means we end up breaching the TPP, we will scrap that out with the other TPP partners," Little said on Tuesday.

TRACY WATKINS/Stuff.co.nz Former NZ Prime Minister Helen Clark talks about the TPPA.

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Labour would present its case to a committee set up under the TPPA rules and argue it out, Little said.

"It might be confrontational but it'll be the only way we can fight it out."

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Some countries in the TPPA already had restrictions on house sales and he would "point that right back" at them.

He said the suggestion Labour could instead impose a 100 per cent stamp duty on foreign buyers under the TPP was a "sidewind - a fudge".

Little and Trade Minister Tim Groser met on Monday evening to discuss the provisions of the TPPA in further detail, after the 12-nation free trade agreement was signed last week.

Little refused to say whether whether Labour supported or opposed the TPPA, saying it was impossible to say whether the TPPA was beneficial to NZ without seeing the full text.

But the TPPA was "here and is a reality".

"The question now for us is what happens when we are in government."

Little earlier told Radio New Zealand the party still had a number of unanswered questions about the deal, but was unlikely to pull out of the agreement if it gained power at the next election.

"Although any party has the ability on six months' notice to walk away from the agreement, from New Zealand's point of view, that'd be a pretty serious call to make.

"I think it is unlikely: we've got what we've got, we're now committed to it because the National Government has made us committed to it, [and] we will deal with that when we are in government."

There would be some benefits from the deal, and it appeared to meet Labour's bottom lines on protecting the Treaty of Waitangi and drug buying agency Pharmac.

However, there did not appear to be material benefits for dairy, and no-one had yet done a full assessment of its benefits, he said.

"It's not the gold standard the Government claimed of it. It is equally not the fearsome monster I think was claimed of it by others as well."

Asked about Labour's reaction to other countries breaching TPPA deals that favoured New Zealand, Little drew a distinction between issues involving free trade and market access and those things that limited a Government's ability to act in the best interest of citizens.

No vote to ratify the TPP is taken, but law changes needed to bring it into effect are debated and voted on in Parliament.

Meanwhile Key said "most rational New Zealanders" would support the TPP because it opened markets and reduced tariffs and costs for exporters.

He said if Labour wanted to continue to look like an opposition, opposing things for the sake of it, they should oppose the TPP.

'If they want to look like a government in waiting and are serious about people's jobs they should think about voting for it."

Shortly before Little's meeting with Groser, Key had encouraged Labour to back the trade deal in the spirit of bipartisan co-operation.

Key said he would prefer for Labour to support the TPPA given the two parties had been "locked at the hip historically when it comes to trade deals".

"In the end if Labour don't vote for it, it says a lot more about Labour than it says about TPP. It just means they're not thinking like an alternative government - they're thinking like the opposition," Key said.

Key said Labour only needed to look to comments by its former leader, Helen Clark, to know that the deal was a must.

"She made it clear New Zealand couldn't be left out of the TPP and she's absolutely right."