The United Nation's refugee arm has urged Australia to lift its game and ensure there's proper care for people detained in Papua New Guinea following the suicide of a Sri Lankan Tamil.
The 32-year-old's death on Monday morning was the sixth refugee fatality on Manus Island in four years.
Australia's immigration department confirmed the death at Lorengau Hospital but directed inquiries to PNG authorities.
Refugees and asylum seekers on the island held a memorial service for the man on Monday afternoon and it's believed his family in Sri Lanka have been notified.
Refugee Action Coalition spokesman Ian Rintoul confirmed the man had been facing rape charges against a local woman following an alleged incident at a motel last year.
The matter was yet to go to court and the man had intended to vigorously defend the charges, Mr Rintoul said.
Sudanese refugee Abdul Aziz said the man had been his roommate before he moved to the transit accommodation centre outside the detention complex four months ago.
He said his friend had applied for resettlement in the US but was yet to hear back on the outcome.
'He was nice guy and quiet guy,' Mr Aziz told AAP on the phone from Manus Island.
'In the past few months he's been having... mental problems and was in need of care.'
Mr Aziz said after a recent psychiatrist appointment the man had been kept in isolation at the detention centre for four to five days before he was sent to Lorengau.
'If he was offered appropriate health care and support he wouldn't have to take his own life,' Mr Aziz said.
'There are not enough doctors or proper treatment.'
The local magistrate on the island will be conducting a coroner's investigation over coming days.
The United Nations High Commissioner for Refugees said Australia had an ongoing responsibility to provide critical services to asylum seekers and refugees it has transferred to Papua New Guinea and Nauru.
This is despite the fact the detention centre on Manus Island is due to be closed later this month.
'Once again, such tragedy highlights the acute vulnerability of refugees and asylum-seekers under Australia's offshore processing approach and the need for proper care,' the agency said in a statement.
Human Rights Watch director Elaine Pearson was on Manus Island less than a fortnight ago and witnessed the heavy toll on refugees' mental health.
'Australia's experiment in human suffering needs to stop immediately,' she said.
The suicide is the second refugee death on the island in as many months.
The body of Iranian refugee Hamed Shamshiripour was found near refugee accommodation in early August.
Meanwhile, more than 50 refugees last week left Manus Island and Nauru for a new life in the US. (Sky News)