Advocates say a 26-year-old Iranian asylum seeker being held on Nauru has been found dead in his family's tent.
An asylum seeker being held on Nauru has reportedly taken his own life.
Advocacy group the Refugee Action Coalition said the 26-year-old Iranian man was "found dead inside his family's tent" on Friday morning, "believed to have suicided".
The man is said to have been found by his wife, with the regional processing centre placed in lockdown.
Refugee Action Coalition spokesperson Ian Rintoul told SBS News "he was a healthy young man, who was quite athletic."
"His younger brother has said how much his brother had struggled with depression," he said.
"News of the man's death has shattered the asylum seekers and refugees on Nauru.
"People have been kept for five years on Nauru. People have been left without hope ... There have been so many warnings, but the toll mounts day by day; the neglect continues. So many cases of medical neglect."
Natasha Blucher, the detention advocacy manager at the Asylum Seeker Resource Centre, said the man's death was another indication of the policy failure of offshore detention.
"This was entirely predictable," Ms Blucher said.
"These people have been kept in limbo, their extreme suffering is no way to live ... What we have started to see is a lethal hopelessness."
Ms Blucher was particularly scathing of the mental health support that these individuals receive, which she called "substandard" and "overwhelmed".
She said the man is the 12th person to die in Australia's offshore detention centres and that "the majority have been suicides".
A Rohingya refugee from Myanmar died last month on Manus Island after jumping from a bus.
Canberra has tried to resettle those recognised as refugees to third countries such as the US, and more than 100 have been moved there, according to refugee advocates.
But the Refugee Action Coalition says 1,600 people remain on Nauru and Manus.
The offshore policy is designed to deter people embarking on treacherous sea journeys, but the United Nations and other rights groups have criticised the camps' conditions and long detention periods.
SBS News has contacted the Department of Home Affairs for comment on the individual and information about mental health services that are available on Nauru.
Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14, Suicide Call Back Service on 1300 659 467 and Kids Helpline on 1800 55 1800 (for young people aged 5 to 25).
Additional comment: AAP, AFP