Ismail Hussaini had just finished soccer practice, which was his main motivation to wake in the mornings at the Christmas Island detention centre, when he saw a fellow refugee try to kill himself.

A few days after the unsuccessful suicide attempt, the then 17-year-old walked into a room where the same refugee smashed himself on the head with a mirror.

"After security guards took him to medical there was so much blood left all over the room, and children had seen it," he said.

"I always saw people cutting their arms, their heads ... a lot of people just cried all day and would fight over little things because they were so traumatised. Others just wanted sleeping tablets to keep them asleep for as long as possible."

Mr Hussaini said he fled Afghanistan in 2011 aged 17 and endured eight days on a leaky boat when he was intercepted by the navy off Australia's north-west coastline.

The asylum seeker spent 2½ months at the Christmas Island detention centre before he was taken to Wickham Point detention centre near Darwin for three more months.

Now 22, Mr Hussaini is studying journalism at the University of Canberra and is grateful for his opportunity to live in Australia.

But he called for the closure of all offshore detention centres and faster processing for onshore detention to save the mental health of detainees.

"There is so much self-harm, even on onshore detention centres where there are good facilities, because people are left there for years not knowing where they'll be sent [to live]. It was devastating," he said.

"Every day was so hard sitting behind that fence, watching the cars drive past and being treated like a prisoner. It was like that in detention centres run by Australians, I know it would be much worse on Manus Island and Nauru."

Mr Hussaini was speaking out in response to the 2000 incident reports detailing trauma suffered at Nauru, most recently evidenced in Guardian Australia's release last week.

Some of the files, including a harrowing account of a Nauru guard bashing a toddler at the detention camp, was written by Canberra-based whistleblower Toby Gunn, who recently spoke to The Canberra Times about his firsthand experiences on the island which exposed a pattern of systemic abuse and neglect of children who sought safety from him.

Days after the Nauru files were released and more than three months after PNG's Supreme Court found the Manus Island detention centre was unconstitutional, Papua New Guinea announced that Australia agreed to close the Manus Island facility.

But Immigration Minister Peter Dutton insisted Nauru would remain open as a deterrent to people smugglers.

Mr Hussaini was said the Australian government should move all refugees that were still kept offshore to onshore detention centres, where living conditions are "good," but that the unbearable uncertainty caused by indefinite detention harmed people despite having better facilities.

"People must be treated like humans."

At 5.30pm on Tuesday, August 23, the Canberra Refugee Action Committee will hold a protest rallying for the closure of offshore detention centres, on the corner of Northbourne Avenue and Barry Drive.