A Kiwi man who committed "barbaric" violent acts in Australia will be deported back home despite his protests that he will commit further crime in New Zealand.

Silao Robert Termorthy Sau moved to Australia in 2009 but has been ordered to leave the country after committing a string of violent crimes, including while he was at an immigration detention centre on Christmas Island waiting for his case to be heard.

Now aged about 28, his special temporary visa was cancelled in 2016 after authorities ruled he failed to meet character grounds because of his "substantial" criminal record.

SCOTT FISHER/FAIRFAX NZ Many offenders deported from Australia have spent time in detention centres like this one at Christmas Island.

He appealed that decision, but the Administrative Appeals Tribunal has ruled that his criminal history - described as barbaric, brutal and cruel - entitled the Australian public to be protected from him.

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In 2011 and 2012 he was convicted of multiple armed robberies, causing injury, arson and theft, the tribunal judgment said.

In one assault a man was punched to the ground, resulting in his glasses becoming embedded in his eye. Another was struck over the head with a golf club and another hit in the face with a bottle.

Later that same day Sau and his group pulled a taxi driver from his car, punched him in the face, and then set his car on fire.

In another attack three people were assaulted and robbed, including a woman who was punched and kicked and one man who had his head stomped on.

Sau was remanded in custody, where several of his inmates reported being scared of him and needing protection, the tribunal judgment said.

He was found with prohibited goods including weapons, cigarettes, drugs and matches and was reported to have been aggressive to a nurse, and bragged of assaulting inmates, though no action was taken against him.

After being transferred to the detention centre at Christmas Island, a controversial custody facility because of its remote location and poor conditions, Sau stomped on another detainee's head following a planned attack by a group.

Security footage captured the assault, and was watched by immigration authorities.

Sau said he was defending himself but the Administrative Appeals Tribunal said it was a "brutal attack and had nothing to do with self defence".

In his plea to authorities not to deport him, Sau said his crimes were minor, that he had fallen in with the wrong crowd and his offending was the result of his heavy drinking.

In a letter to the National Character Consideration Centre, Sau wrote, "I truly believe I am a different person now, everything I have learned from addressing my offending behaviour and also the support of my family have been the reasons for this.

"I have changed my life, and my family have been a big part of this, they've been there for me for the last five years and I don't know what I would do without them.... I owe my family so much and deeply regret getting involved in the criminal offences, I apologize [sic] to everyone whom was affected by my actions."

In another letter he described himself as being "fully rehabilitated" but the authority noted the letter was dated four days after the stomping attack at Christmas Island.

Sau said he had no family or support in New Zealand and, if deported, there would be a "high risk" he would return to crime and be coerced into joining a gang.

"With respect to Mr Sau, the same concern clearly arises if he were permitted to remain in Australia. That problem is not unique to New Zealand. It is the same problem which led, in part, to his criminal behaviour in New Zealand," appeal tribunal member Egon Fice said in his decision.

In rejecting the appeal at a May hearing, Fice said the Australian public needed to be protected from Sau and although a psychologist deemed Sau a good candidate for rehabilitation, Fice said Sau's conduct was contrary.

"I have also found that Mr Sau's statements about being rehabilitated and remorseful were simply statements. They are not supported by his conduct. Therefore, I find that Mr Sau does present a serious risk to the Australian community should he be allowed to remain in Australia."

In 2014 Australia began deporting foreigners who had served prison sentences of more than a year.

Many cases have been reported of people spending most of their lives in Australia, and having to move back to New Zealand where their families no longer lived.

Figures show about 30 per cent of the deportees returned to New Zealand have committed further offending here.

Labour MP Kelvin Davis has previously said deportees with no support systems became desperate.