US Secretary of State Rex Tillerson will meet Prime Minister Bill English in Wellington next week.

United States Secretary of State Rex Tillerson arrives in Wellington next week, in what's being called a major show of American interest in the Asia-Pacific region and "big deal" for New Zealand.

Tillerson will meet Prime Minister Bill English and Foreign Affairs Minister Gerry Brownlee in Wellington on Tuesday.

Brownlee said meetings would be held to discuss "some of the world's most pressing issues and to further promote our economic ties".

Observers said regional stability, counter-terrorism, and military commitments in Iraq and possibly Afghanistan would be discussed, as would trade issues including the afflicted Trans-Pacific Partnership (TPP).

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Former defence minister Wayne Mapp said Tillerson's visit was a pragmatic way to show continued US interest in the Asia-Pacific, and a sign Donald Trump's insular campaign rhetoric was not translating into foreign policy doctrine.

The Pacific rim was the most important region in the world, Mapp said, being home to the world's two most powerful nations in the US and China.

"New Zealand can't afford to have one of them saying 'we're not engaged'.

"New Zealand's fundamental interest, more than anything else, is stability in our region."

Tillerson, a former ExxonMobil​ chairman frequently described as a hard-nosed realist, was widely travelled and one of the two most respected figures in the Trump administration, Mapp said.

The other was Secretary of Defense James Mattis.​

Mapp said Tillerson had a keen, nuanced understanding of international trade.

Defence issues were also on the agenda.

The Cabinet agreed last year to extend contributions to the joint New Zealand-Australia mission to train Iraqi security forces until November 2018.

But the Trump administration has voiced desires for US allies and partners to contribute more to defence arrangements.

The trip was "a big deal" because for a long time New Zealand had no visits from anyone of significance, University of Auckland political scientist Stephen Hoadley said.

Hoadley, associate professor of politics and international relations, would not be surprised if Tillerson asked English and Defence Minister Mark Mitchell to increase the Kiwi contribution in Iraq.

"I think Bill English and Mark Mitchell will be amenable to that, as long as it's not a drastic increase."

Brownlee said no such request had been received, but if it was, it would be considered.

"New Zealand's contribution in Iraq has been significant and appreciated by our coalition partners. We're looking forward to having productive discussions with Secretary Tillerson."

Deputy Prime Minister Paula Bennett said the visit was very important, though Tillerson planned to be in New Zealand for less than 24 hours.

"It's an opportunity to talk about some of those things we've got in common and have a look at some of those bigger issues happening around the globe," she said.

Tillerson will stop in Sydney on Monday, along with Mattis.

The pair will attend the 2017 Australia-US Ministerial Consultations with Australian Foreign Affairs Minister Julie Bishop and Defence Minister Marise Payne.

Details on the size of Tillerson's entourage were scarce, but he was expected to bring a smaller contingent to New Zealand than predecessor Hillary Clinton did in 2010.

Clinton brought a delegation of 60, mostly advisers and security staff.

She caught officials on the hop by bringing forward a wreath-laying ceremony herself, requiring Mapp to be called in ahead of time.

Tillerson will use a motorcade for most travel arrangements.

But on major state visits, it was common for a dignitary's timetable, even on their arrival, to still be in a relative state of flux.

It was unlikely Wellington's CBD would be shut down if Tillerson's convoy travelled through.

During Chinese Premier Li Keqiang's visit earlier this year, police stopped traffic for about 15 minutes before his motorcade passed.

Police would not say whether snipers or armed personnel would be deployed.

Superintendent Chris Scahill​ said normal police operations in Wellington would be unaffected. Wellington district police would lead operations, with oversight from Police National Headquarters.