New Zealand has deported a Pacific islander who launched a failed bid to become the world's first climate change refugee, the man's supporters said Thursday.

Ioane Teitiota was sent to Kiribati on Wednesday after exhausting all avenues of appeal in his four-year battle to stay in New Zealand.

Teitiota, 39, had argued that he should not be sent back to Kiribati as rising seas threaten to deluge the island nation of 100,000 people, making it unsafe for him and his family.

His pastor, reverend Iosefa Suamalie, confirmed Teitiota's departure after the expatriate Kiribati community's last-minute pleas were turned down.

Suamalie said the future was uncertain for Teitiota's wife and three New Zealand-born children, who are expected to follow him to Kiribati next week.

"What we've been doing is trying to save this family seeking asylum here in New Zealand because of a form of persecution by climate change," he told Radio New Zealand.

"Going back to Kiribati, there is no life, there is no hope. We are sending back the children to a place that is not safe for them."

Low-lying Kiribati suffers from a range of environmental problems that have been linked to climate change, including storm surges, flooding and water contamination.

The situation is so dire that Kiribati's government has bought 2,000 hectares (5,000 acres) of land in Fiji to act as a farm for Kiribati if salt-water pollution means the former British colony can no longer produce crops.

Teitiota moved to New Zealand in 2007 and overstayed his visa, coming to the attention of police in 2011 over a minor traffic violation.

Earlier this year, New Zealand's Supreme Court acknowledged Kiribati faced challenges linked to climate change.

But it ruled Teitiota did not meet the legal definition of a refugee because he would not face persecution if he returned home.

Prime Minister John Key this week said Teitiota's argument lacked credibility and he had to abide by New Zealand's laws.

"I'm sure people feel for the guy... (but) in my eyes, he's not a refugee, he's an overstayer," he said.