Jacinda Ardern hired an advertising agency to photograph and film her New York trip.
In the past, New Zealand Prime Ministers have had a staffer from their offices take photos, but Ardern had a crew of three from agency Augusto's New York office.
They have been used on social media and Ardern told the Herald on Sunday some would also be used for campaign purposes.
This morning the Prime Minister's office clarified that the images would be used for "stock footage and social media content that the government would be using in the future", which they said is inside the rules.
But the Opposition has accused Ardern of breaching the rules around campaign spending.
Ardern defended the decision to contract the agency. She said Augusto's fee would be paid for out of Labour's Leaders' Budget, a pool of taxpayer-funding which political parties can use for communications purposes.
"They did social media for us, they did a bit of work on the last campaign and so they're doing work for us now, helping build up our stock footage and stuff. Campaign stuff."
The footage and photos - including for some occasions to which media had no access - were also made available for media to use, including the Herald.
The Augusto crew were not part of the formal delegation, Ardern said, and because they were based in New York, the costs did not include air travel or accommodation.
Ardern said she did not know what the fee was for Augusto's work.
"I haven't looked at what the cost is, but we have a limited Leader's Budget so it won't be excessive. We wouldn't have done it if it was significant. It was cheaper than bringing someone here."
The Prime Minister's office said today that due to the "packed and busy nature" of the New York schedule it was going to be "impossible" for the media to attend all of Ardern's events.
"We contracted Augusto to provide film and photograph to the New Zealand media for all events that the PM attended and to collect social media content. That is entirely within the rules," a spokesman said.
"Our understanding is that past prime ministers have brought over a photographer for this purpose - we considered that but it worked out cheaper to use someone who was already in New York, this option saved the taxpayer money.
"The Prime Minister was referencing the fact that what has been captured this week would be used as stock footage and social media content that the government would be using in the future. We used Leaders Budget to do that and it is within the rules.
"Most people now get a lot of their news via social media. Other world leaders share film and photos of what they are up to and there was a lot of interest in what the Prime Minister was doing in New York. This contract just reflects what is now pretty normal overseas."
National's deputy leader Paula Bennett said the filming would be an issue if the footage was used for campaign purposes.
"What stands out here is that the Prime Minister has said she is using her Leader's Budget and the footage will be used for political campaigning.
"This is against the rules and I would urge the Prime Minister to clarify whether taxpayers' funds will be used for the Labour Party to campaign."
She said it wasn't unusual for a leader to document their travels with photo and video footage, but former Prime Minister John Key would use a staffer to do so.
"When John Key was PM he would occasionally have a photographer on international trips, but only if they travelled on the Airforce 757 where there weren't additional flying costs," she said.
A National spokeswoman said no one in her office recalled Key hiring a local photographer in another country however sometimes a local New Zealand embassy would do so.
Act Party leader David Seymour said he didn't have an issue with politicians using their Leader's Budget as they saw fit, but thought Ardern would be better getting policy advice, "and maybe get some help managing Winston while she's at it".
- Additional reporting: Nicholas Jones