However, with Expedition Earth pair Topher Richwhite and Bridget Thackwray now released from detention, New Zealand is now stepping up its criticism of the Iranian regime.

On Monday, Foreign Minister Nanaia Mahuta said New Zealand hoped to send a "strong signal" by withdrawing from bilateral human rights talks with Iran.

"Aotearoa New Zealand continues to be appalled by the use of force by Iranian authorities in response to peaceful demonstrations following the death of Mahsa Amini last month," she said.

"Violence against women, girls or any other members of Iranian society to prevent their exercise of universal human rights is unacceptable and must end."

New Zealand is now calling for an investigation into the use of force by authorities, with over 200 believed killed in the past six weeks.

Ms Ardern has also signed an open letter supported by some of the world's most high-profile female leaders to remove Iran from the United Nations Commission on the Status of Women.

Others to have signed include Michelle Obama, Hillary Clinton, Christine Lagarde and Malala Yousafazi.

The actions show a sharp uptick in New Zealand's diplomatic response on Iran, coinciding with the release of the two travel bloggers.

Mr Richwhite, the son of rich-lister David Richwhite, and Ms Thackwray were kept in Iran for three months by the regime for allegedly breaking Iranian law on fliming in sensitive locations.

The New Zealand government opted to use 'quiet diplomacy' to secure their release, successfully imploring Kiwi media outlets not to publish stories on the pair while negotiating with Tehran in the background.

Quiet diplomacy has been criticised by many, including Australian academic Kylie Moore-Gilbert, who spent over two years in Iranian prisons before a negotiated release in a similar way.

"There is very little precedent for quiet diplomacy working in Iran that we know of. This case may be one exception," she told AAP.

"The crucial aspect is time. If a government escalates cases of state hostage taking to the highest political levels quickly enough, robust diplomatic action could be taken."

Dr Moore-Gilbert highlighted an Iranian report about the pair's case on October 25, prompting Kiwi media outlets to also report on the case.

An announcement of the pair's freedom then followed on October 26.

The Ministry of Foreign Affairs and Trade declined to answer questions around the case, citing policy not to comment on consular issues.

However, Kiwi officials reached out to other countries and people who were in similar situations to the Expedition Earth pair.

"The universal view was that we would have a greater likelihood of a quicker resolution and more successful resolution if we were able to conduct that diplomacy directly with Iranian officials without the public scrutiny," Ms Ardern said.

Ms Mahuta suggested the proof of the pudding was in the eating.

"It did work. They are out, they are safe," she said.

On Monday, Ms Ardern agreed she was now freer to act and respond to the Iran human rights crisis than she was with the pair detained.

However, she insisted "it did not stop us from taking a very clear position".

"I will push back on any suggestion that we did not condemn Iran. We did," she said.

"New Zealand managed to take a strong position on Iran, whilst also working very hard to ensure that two New Zealanders in a very difficult situation could leave.

"It is clear however, we are now in an improved position to be able to continue to ramp up our response."

Australian Associated Press