Former Prime Minister Jacinda Ardern was quick to call the Solomon Islands-China security pact last year "gravely concerning", but Chris Hipkins isn't giving the United States' new deal with Papua New Guinea the same label.

The two agreements are "different", Prime Minister Hipkins said on Monday during a visit to PNG's Port Morseby for meetings with the country's leadership and other world leaders. He said the US-PNG deal was "very transparent" and an extension of an existing relationship the two countries have.

"I don't want to get into a comparison game on this. They are different situations. Our language is, I think, reflective of our position," Hipkins said.

The US on Monday confirmed it was signing several new agreements with PNG, including a bilateral defence cooperation agreement which will allow the two countries to "enhance security cooperation". It is expected to publish the text of the agreement at a later date.

US Secretary of State Antony Blinken will be in PNG to sign the deals and meet with representatives from Pacific nations, including with Hipkins. 

Hipkins on Monday told reporters he had spoken with PNG Prime Minister James Marape about the security agreement. He said he listened to Marape's view on what the deal would achieve for PNG - a "strengthened ongoing relationship" with the US.

"I would like to acknowledge this is not new territory for Papua New Guinea," Hipkins said.

"They have existing security arrangements with the United States. This is not just about security. It extends to a range of other things, including electrification and so on. I would see this more as an extension of an existing relationship."

Last year, when it emerged China was on the brink of signing a security pact with the Solomon Islands, New Zealand was among the countries that reacted with concern about it leading to a greater militarisation of the Pacific.

"We do see this as gravely concerning," Prime Minister Ardern said in March last year.

At the time, there were few official details about the Solomons-China deal, but leaked documents suggested it could lead to China stationing warships at the island nation.

"While such agreements will always be the right of any sovereign country to enter into, we have made clear to both Solomon Islands and China our grave concerns at the agreement's potential to destabilise the Pacific region's security," Foreign Affairs Minister Nanaia Mahuta said after the deal was signed in April.

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Hipkins was asked on Monday why New Zealand expressed grave concerns about that deal, but wasn't using the same language when it came to the US-PNG agreement. 

"This is a very transparent arrangement," Hipkins said.

"We know what's in the arrangement and we can see it's an extension of an existing relationship. It isn't just about military presence, it is also about development, it is about electrification, it is about a range of other different issues where there is an existing, solid relationship that is being built on here."

He said the parties to the agreement will have their own views, but "from a New Zealand perspective, we do see them as different".

Hipkins said each country in the Pacific has a right to have its own view on the situation and he was representing New Zealand's position.

"We certainly know what to expect from the US in terms of our existing relationships with them. I don't want to get into a comparison game on this. They are different situations. Our language is, I think, reflective of our position."

The Prime Minister also made the point that while New Zealand doesn't support militarisation of the Pacific, "military presence doesn't necessarily signify militarisation". He gave the example of New Zealand sending military assets to island nations to assist with the recovery from natural disasters. 

"We shouldn't assume that all military partnerships are necessarily about conflict," he said.

PNG PM Marape has reportedly said people do not need to fear the new security deal, saying it is "not a new thing". However, he has said it will lead to an "increased presence" by the US in his country. 

Mahuta wouldn't provide much comment last week on the US-PNG deal, but said her view about the militarisation of the Pacific was "country-agnostic". 

"I think the [Pacific Islands Forum] have highlighted that the Boe Declaration, which reaffirms our commitment to regional security issues, is something to be upheld. I am sure that Pacific partners as they make their various determinations about their security interest will keep that in mind."

New Zealand has stressed over the past year that Pacific Island nations should look within the region for assistance on matters, citing the Biketawa Declaration.