A Pacific islander is seeking recognition as the world's first climate change refugee in New Zealand as rising seas threaten his low-lying homeland, the man's lawyer said Thursday.

Ioane Teitiota, 37, launched an appeal this week against a decision by New Zealand immigration authorities to refuse him refugee status and deport him to Kiribati in the central Pacific, lawyer Michael Kitt said.

Kitt acknowledged Teitiota's New Zealand visa had expired but said he should not face deportation because of the difficulties he would encounter in Kiribati -- which consists of more than 30 coral atolls, most only a few metres (feet) above sea level.

He said rising seas had already swamped parts of Kiribati, destroying crops and contaminating water supplies.

"Fresh water is a basic human right... the Kiribati government is unable, and perhaps unwilling, to guarantee these things because it's completely beyond their control," Kitt told Radio New Zealand.

He said Teitiota's case had the potential to set an international precedent, not only for Kiribati's 100,000 residents but for all populations threatened by man-made climate change.

If his appeal is successful Teitiota would become the world's first climate refugee, Kitt said.

As the environmental problem worsened a new class of refugee was emerging that was not properly covered by existing international protocols, he added.

"It's a fluid situation, eventually the courts and legislatures are going to have to make a decision on how we deal with this."

Kiribati is among a number of island states -- including Tuvalu, Tokelau and the Maldives -- the UN Human Rights Commission is concerned could become "stateless" due to climate change.

Kiribati government's has raised the prospect of relocating the entire population or building man-made islands to rehouse them if predictions the sea will rise by one metre (3.25 feet) by the end of the century prove accurate.

It has also moved to buy 2,000 hectares (5,000 acres) of land in Fiji to act as a farm for Kiribati if salt-water pollution means the islands in the former British colony can no longer produce crops.

Kitt said deporting Teitiota was like forcing a gay person to return to a country where they faced persecution, or a domestic violence victim to go to a nation where women's rights were not protected.

In refusing Teitiota's application earlier this year, immigration authorities argued that the Kiribati man could not be considered a refugee because no one in his homeland was threatening his life if he returned.

Kitt countered by arguing that the environment in Kiribati effectively poses a threat to Teitiota and the three children he fathered in New Zealand, who will have to return with him if he is deported.

"Mr Teitiota is being persecuted passively by the circumstances in which he's living, which the Kiribati government has no ability to ameliorate," he said.

Kiribati joined a number of other Pacific states last month in signing the "Majuro declaration" on climate change, which calls for urgent action on an issue where small countries are bearing the brunt of impacts caused by major polluters.

A judge in the Auckland High Court reserved a decision on Teitiota's appeal on Wednesday and the judgement is expected to be released by the end of the month.