The government remains divided over the second tranche of gun reforms and New Zealand First leader Winston Peters cannot say when an agreement might be reached.

Photo: RNZ /Dom Thomas

That means any hope Labour had of passing legislation in time for the 15 March anniversary of the Christchurch mosque shootings is now lost.

While there was near unanimous support for the banning of most semi-automatic weapons and some gun parts in the immediate aftermath of the attacks, there is increasing division between parties - including the coalition partners - on what shape the latest changes should take.

Police Minister Stuart Nash said he would not describe the hold-up as New Zealand First stalling.

While the government would have liked the bill passed by 15 March, Nash said that was not the priority.

"That's not the important thing, the important thing is we get an arms bill and a piece of arms legislation that is transformational - and that meets our requirements," he said.

"There's change that has to be done before we get the right bill and I think getting it right is more important than getting it done to a certain date."

In April, a law making most semi-automatic firearms illegal passed with near unanimous political support in the wake of the mosque attacks that left 51 people dead.

The National Party joined forces with the government back then.

However, Parliament is once again divided on the second tranche with the opposition pulling its support. That means Nash has to rely on New Zealand First to get it through.

The bill includes a firearms registry, harsher penalties, and a warning flag system around a fit and proper person test.

New Zealand First is still negotiating three areas; an independent arms agency, rights for farmers dealing with pest control, and exemptions for sporting shooters.

Peters said no agreement had been reached.

"Well the fact is we're having constructive talks with the Minister of Police," he said.

"These are still ongoing as I understand it from my latest briefing. I don't know when they'll be resolved, but we are in a positive way going forward to ensure everyone is in the same place and everyone is happy with the outcome."

Peters said the anniversary of the attacks was not part of his party's thinking.

"We are driving things to make sure we've got a satisfactory resolution, that's what's paramount in our mind."

But if New Zealand First doesn't get its way, will it pull support for the bill?

"We don't deal with hypotheticals, we deal with facts... we don't go into a serious purpose on the view we might fail, our job is to make sure we succeed in the best interests of the country and dare I say it the government,'' Peters said.

National Party police spokesperson Brett Hudson said the opposition detailed 13 bottom-lines for its support but only two have been dealt with.

"We'll have to see to what extent New Zealand and Labour have concocted some series of amendments - but I have put in a number now that will deal with the outstanding issues - and if the government is prepared to support those then they will have met the requirements we set out."

Hudson said the government had the numbers to get the bill across the line but that relied on New Zealand First's demands being met.

Meaning once again, New Zealand First and Peters have Labour backed into a corner.

With an election just six months away, the clock is already ticking on getting the legislation passed.