It's unfair a convicted New Zealand rugby league player is allowed to stay in Australia while others on less serious charges have been sent back, a lawyer says.

Photo: PHOTOSPORT

It was confirmed late last year that Russell Packer would not be deported after he signed a two-year deal with the St George Illawarra Dragons in the NRL.

Packer repeatedly punched and stomped his victim in a drunken attack in Sydney.

Packer was sentenced in 2014 to two years in jail for the attack on his New Zealand victim. He was paroled after his sentence was cut to 12 months on appeal.

Lawyer Greg Barns, who represents some New Zealand detainees, said it was extraordinary he had been allowed to stay.

"It certainly seems to indicate that if people are in certain positions in society for example, they are champion footballers they might have a better chance of staying because there've been plenty of other New Zealanders who've been sent back to New Zealand or threatened with deportation, whose cases were less serious."

Mr Barns said it raised questions about the consistency of the system and he wanted the Australian government to explain its actions.

Campaigners' groups have also said allowing Packer to stay in Australia after being jailed for assault made a mockery of the government's detention and deportation policy.

Erina Morunga-Anderson, of the campaign group Iwi n Aus, said his was the first case her group had heard of under Australia's new visa rules where a criminal had not been sent to a detention centre while a final decision was made about deportation.

"He's the first person we know of that didn't get his visa cancelled instantly the moment he finished his jail sentence and he was able to appeal it from the comfort of his own home," she said.

"And on top of that, Peter Dutton [Australia's immigration minister] turned around and said 'Well, I think he's reformed, I think he's remorseful' and all that kind of stuff and therefore I'm going to give him a second chance'. That's the first time we've heard of anything like that."

She said Packer's crime was more serious and more recent than other detainees who had been deported or were awaiting a decision.

Photo: RNZ / Claire Eastham-Farrelly

More than 3000 people signed a petition calling on the government to let Packer stay in Australia.

Vaelua Lagaaia, who is being detained at Villawood detention centre, said it was due to that popularity that Packer was allowed to stay and others were not.

"We don't understand what the difference is between our cases and his case which was a serious assault case, you know a lot of people that are in detention now don't even have serious crimes and yet they are in detention," he said.

"So it's very confusing for us here as New Zealanders where we think if you are a football player or popular the law doesn't account for someone like that."

The father-of-two, who has lived in Australia since 1993, was jailed for obtaining money by deception.

He said detainees spent Christmas locked up, knowing their files were lying untouched as case officers were all on holiday.

The latest figures showed 194 New Zealanders were being held in detention centres, down from a high of 213 in October, but still more than double the number in March.

Another advocate working to release detainees, Ema Williams, of IndigenousWise Incorporated, said she was happy for Packer but the lack of a judicial process was frightening.

"The inequality and maybe even the discrimination between the cases disturbs me," she said.

"We as Australian citizens, as New Zealand citizens, need to wake up to this and say 'what's happening'? We live in a democratic society.

"Why is it that in certain issues and certain situations we have decided to give power to give individuals and their entourages the right to dictate what liberty looks like?"