A Kiwi who joined Islamic State and is now detained in a Kurdish prison will have to find his own way out of Syria, Prime Minister Jacinda Ardern says.

Photo: RNZ

Nicknamed the 'Kiwi Jihadi', Mark Taylor told the ABC he fled the Islamic State group in December and surrendered to Kurdish forces because life had become unbearable.

Ms Ardern and Justice Minister Andrew Little would not be drawn on the specifics of the case at a post-cabinet press conference today but said they had warned New Zealanders of the risks.

"New Zealand has made it very clear from the outset that New Zealanders should not travel to Syria. Further, it is clear that it is unlawful to join and fight with a terrorist organisation as Mark Taylor has done."

His actions in joining IS and travelling to Syria to fight for them has created potential for legal ramifications in New Zealand, she said.

"As with any New Zealand citizen overseas, if they wish to return to New Zealand then a journey specific emergency travel document can be issued under Section 23 of the Passports Act 1992."

The absence of New Zealand diplomatic representation in Syria meant the ability of the government to assist any citizens there was "severely limited", Ms Ardern said.

She said Taylor would probably have to travel to Turkey to get the documents he needed.

"We have consistently told Mark Taylor that we cannot help him obtain a travel document, he would need to make his own way to a country where New Zealand has consular representation, something that in his current situation will be difficult to do."

Taylor only had a New Zealand citizenship and the government had an obligation not to make people stateless, she said.

While Ms Ardern acknowledged the government's obligations to citizens overseas, she reiterated that they were limited in what they could do as they had no connections with the forces detaining him.

She also said she did not know the conditions in which he was being detained.

She said the safety of New Zealanders was a priority and contingency plans had been under way for some time, involving police and other agencies.

"I can assure you that we have long had plans in place in the event that a New Zealand citizen supporting ISIS in Syria were to return. It would involve a comprehensive response and management plan for any individual.

"I am confident that we have the means to keep New Zealanders safe.

"Bringing terrorists to justice is something the government takes extremely seriously."

She said any New Zealander suspected of participating in such activities should expect to be investigated upon their return.

"Police have powers under a number of acts and I am assured they will utilize them."

If Taylor does manage to make it to another country where New Zealand has consular representation, Mr Little said he could only be aided to the extent of checking he was okay but would not provide legal assistance.

Mr Little said he could not say what legal ramifications Taylor could face if he returned.

Ms Ardern said a very small number of New Zealanders were thought to have been in Syria with ISIS.

A police spokesperson would not discuss matters regarding specific individuals, but indicated that Taylor would face investigation if he returned to New Zealand.

"If a New Zealand citizen suspected of associating with a terrorist group were to return to New Zealand they would be investigated under New Zealand law. The circumstances of these individuals is highly complex and any investigation or possible judicial proceedings would be considered on a case by case basis," the spokesperson said.

Taylor's history

In 2015, the US government declared Taylor a global terrorist after he encouraged attacks in Australia and New Zealand and appeared in an IS propaganda video.

In 2009, he was arrested in Pakistan for trying to gain access to Al Qaeda.

In 2010, he was deported by ASIO after he was assessed as being a security risk. Taylor had lived in Australia on and off for 25 years.

Taylor said he would be surprised if New Zealand did not take him back.

"If they do take me back, most probably I'll be spending a couple of years in jail," he said.

And he had an apology, of sorts, for his home country.

"I'm sorry for causing too much trouble and being a bit hot-headed and flamboyant in my approach… I don't know if I can go back to New Zealand, but at the end of the day it's really something I have to live with for the rest of my life."

- with additional reporting by ABC