A Fijian man hopes the new Immigration Minister will stop his intellectually disabled son being deported.

In his Kelston flat in Auckland, Lalit Narayan cares for his son Sagar, 20, who needs looking after full time.

"We have to look after him. If I have to work, my sons look after him."

Photo: RNZ / Tom Furley

Mr Narayan came to New Zealand with his family in 2008, and left Sagar in the care of his parents in Fiji.

Soon after, his mother died and his father grew ill so Mr Narayan moved Sagar to Auckland in 2009, where he was able to stay on various short term visas.

He applied for permanent residency for Sagar but was denied, and Sagar has been told to leave the country by Friday.

"We have got no place to take Sagar back to Fiji and Sagar can't look after himself ... if he is going to go by himself he's going to die, he's going to cry, he's not going to survive by himself."

He no longer has any family who can look after him there and Mr Narayan said he could not leave his children alone in New Zealand or remove them from their studies to Fiji.

"He can't understand anything, if you're going to send him back to Fiji he won't know anything. He only knows his mum and dad that's all.

Lalit said his son's application was denied because of the $16,000 cost he'd bring the government, primarily for education.

However, he argued his son had only been to the GP twice in the eight years since he had been in New Zealand and never attended school.

"I never took a single cent from the government.

"At the end of the day I am paying the tax also, I've been paying tax for roughly 10 years now."

He said his local MP, Labour's Carmel Sepuloni, had written a letter to the Immigration Minister supporting him.

He hoped a new Immigration Minister after the change of government might re-evaluate his son's case.

"I plead to him if he can give my son residence for here. I want to look after my son at my cost," he said.

"I want to stay in New Zealand with my family, with my kids and with me. I don't want anybody's taxpayer money, I don't want anything from them. I can look after my son for 20 years, I can look after my son and that's all I want."

Photo: RNZ / Tom Furley

He had not made any plans for Friday and did not know what would happen if nothing had changed by the end of the week.

Immigration lawyer Alastair McClymont said any concern by officials around education costs to the government were no longer relevant as Sagar was now 20 and no longer in the education system.

He said after approaching the Fijian government and enquiries by advocacy organisation IHC, the only option for Sagar in Fiji would be hospital for the rest of his life.

"He's an intellectually disabled 20-year-old who is able to do things by himself in the home with his family. He doesn't need any residential care here in New Zealand but that will be the likely outcome for him if he goes to Fiji."

Mr McClymont said there were few options left.

"If Sagar is detained then there is a possibility of a judicial review of that detention through the High Court looking at New Zealand's obligations to various international conventions," he said.

"But this family, the resources are very limited so we're hoping to avoid that.

"All of the hope is now being placed on a new Minister of Immigration after Thursday, re-looking at Sagar's case."

Immigration New Zealand would not comment, saying the case was before the minister.

RNZ was also unable to contact the office of caretaker Immigration Minister Michael Woodhouse.