Two New Zealand detainees on Christmas Island say they've been punished for trying to expose guards abusing an asylum seeker.
They recently posted CCTV footage from two years ago on Facebook showing Serco guards at the Australian immigration detention centre manhandling the Egyptian asylum seeker.
Watch a copy of the footage:
The asylum seeker, Ossama Wahab, originally posted the video online himself.
He has accused the Australian Federal Police of covering up his complaint of being badly injured in the April 2015 incident, but officials say there isn't enough evidence to take action.
The two other detainees posted the footage two weeks ago, and one said he was put in an isolation cell after refusing to remove the video.
"They asked us to take the footage down ... Once we refused that then, a couple of days later, they came about four, five in the morning and took us to segregation and started accusing us of trying to start a riot," said Rakhim Mataia, a 22-year-old from Christchurch.
Johanan Andrews, 21, who left Auckland for Brisbane as a five-year-old, said he was put in segregation - an isolation cell where a person is let out for one hour a day.
"I was up there for six days ... I'm getting mistreated in here," he told RNZ on a landline phone from Green 2 compound, one of eight compounds at the centre.
Mr Wahab said he posted the video on Facebook late last month, after fighting for months for action.
He described a guard getting upset with him on the way back from White 1 compound on 23 April, 2015.
The CCTV footage, released by Serco as part of a police investigation, shows a detainee being forced to the floor without any apparent provocation and held there by six guards for three minutes, then dragged off.
Mr Wahab said he was taken to an isolation cell.
"They jump [sic] on me, and they started bashing me ... I mean I couldn't breathe at that time, I was dying ... he's put his knees next to my face, I couldn't even not [sic] breathe, nothing."
Mr Wahab said he lost a tooth and has an injured arm.
Serco and the Australian Immigration Department said in brief statements to RNZ that federal police had found insufficient evidence to take any action.
"The federal police ... they just cover each other's back," Mr Wahab said.
"What do you mean it's not assault ... man, I've got trauma."
Mr Wahab said he pressed assault charges against the guards and believed they were still before the court, but that it was difficult to determine.
Mataia and Andrews said the sort of mistreatment described by Mr Wahab was still occurring, though slightly less frequently than when they both first arrived at Christmas Island nine months ago.
They said there was no one to complain to about abuse.
Mataia, who said he lost his Australian visa after a two-and-a-half year prison term for robbery, said he had witnessed a detainee next-door to his room get cuffed, elbowed and forced to the ground, where guards stood on his head.
When RNZ first spoke on the phone to Mr Wahab, the call was interrupted and he asked RNZ to call back 10 minutes later.
When RNZ called back, Mataia said Mr Wahab had been taken away to be put on a flight to Perth.
Mataia said he feared Mr Wahab was being taken to another detention centre to be deported.
Mr Wahab has said he feared he would be killed in Egypt, like his brother was.
All three detainees told RNZ they wanted to challenge the secrecy maintained by the Australian government around the centre, where it is suspected about 150 New Zealand-born men are being held indefinitely.
The Australian Immigration Department declined to give the number - though it said, as of May, a total of 176 New Zealand-born people were detained in Australian detention centres.