The Labour Party would not support a proposed NZ First members' bill which would force migrants and refugees to agree to New Zealand values, Prime Minister Jacinda Ardern has said.

But the NZ First MP in charge of the Respecting New Zealand Values Bill is not worried about Ardern's comments and said it could be on the table for coalition negotiations in 2020.

The mooted bill, which has not yet been approved by the NZ First caucus, was discussed at the party's annual conference over the weekend.

It has the support of Leader Winston Peters, who said if someone is coming to New Zealand as a refugee, "surely you respect the country you've come to".

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But Ardern does not share her Deputy Prime Minister's thoughts, telling Newstalk ZB's Mike Hosking that Labour would not support it as a bill if it came before the House.

"It's a members' bill and every party is able to put up their own members' bills," she said.

Every MP in Parliament is able to submit members' bills, which are randomly drawn from a ballot to be debated in the House.

Ardern made it clear that the proposed bill "is not government policy" and won't be adopted by the Government if it comes before the House.

Asked if she would have pushed back on the idea, if it was part of the NZ First/Labour Coalition negotiations, she said: "Everything has to be negotiated and our coalition agreement stands from the moment we signed it.

"Everything since then we debate and negotiate."

But NZ First MP Clayton Mitchell, who drew up the bill on behalf of the party's Tauranga members, is not fazed by the Prime Minister's comments.

"This is about protecting New Zealand values, whether or not it gets the support it deserves is irrelevant."

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He said it was not written to be aligned to any other political party.

It could become a members bill, or "something we discuss in 2020 coalition negotiations", he said.

The proposed bill, which is a remit at this stage, will soon go before the NZ First caucus to assess whether it is to become a fully fledged bill.

Mitchell does not know what support it will have in the caucus, but said he will be putting a "strong case" to MPs when they discuss it.

Ardern joins a range of others who have voiced opposition to the proposed bill.

National Leader Simon Bridges called the bill "headline-grabbing nonsense".

New Zealand Refugee Council President Arif Saeid does not support the proposal, neither does the Human Rights Commission.