A refugee held in a Manus Island detention centre run by the Australian government has died.
BuzzFeed News understands the Iranian man's body was found near the East Lorengau transit centre.
Detainees said the cause of death was unclear.
A refugee passed away in #Manus island. He was very sick for long time but Australia did not provide medical treatment for him.
"This guy was mentally ill for a long time; he was thrown in jail instead of hospital," Iranian refugee Amir Taghinia told BuzzFeed News.
BuzzFeed News has been sent photographs which purport to show the man’s body when it was found.
There was a strong police presence in the area where the body was discovered, another Iranian detainee, who asked not to be named, told BuzzFeed News on Monday.
Manus province police chief, inspector David Yapu, confirmed the death of a refugee and said a crime scene had been established, The Guardian reported.
The spokesperson for Australia's Department of Immigration and Border Protection said the department was "aware of a death in Lorengau Township".
"PNG authorities are investigating the matter," the spokesperson said.
Refugees detained at the centre last month told BuzzFeed News conditions were "getting worse every day" as food quality deteriorated, they were no longer able to exercise, and many had "no idea" what their chances of resettlement were.
With the tragic and avoidable death of a 5th refugee on #Manus today we renew again our call that all men on #Manus must be evacuated now.
Detainees have recently protested daily at 2pm over their conditions. Staff have withdrawn power, water and medical services at existing accommodation compounds, which are being progressively shut down.
The complex was last year slated for closure on October 31 this year, after PNG's Supreme Court ruled it illegal.
Men have been forced to relocate to a new camp at the East Lorengau Refugee Transit Centre on the outskirts of Manus province's main town.
Last week was the anniversary of the death of Kamil Hussain, a detainee who drowned at a waterfall on the island.
Kamil Hossein, husband, father, died last year in an Australian concentration https://t.co/xlQTCyTPqW is the annive… https://t.co/9Nse5AUpDb
On Christmas Eve last year, Sudanese detainee Faysal Ishak Ahmed collapsed at the compound, was evacuated and later died at a Brisbane hospital.
In June, a class action seeking damages for almost 2,000 men detained on Manus Island reached a $70 million settlement with the Immigration Department ahead of an expected six-month trial.
The class action claimed that detainees suffered serious physical and psychological injuries as a result of the conditions in which they were held on Manus Island from November 2012 to December 2014.
During that time there were riots at the detention centre (February 2014) in which one detainee was killed and dozens were seriously injured.
#Manus Island 5 refugees now dead due to Oz Gov neglect Australian run 1,671 days 3 billion $ spent 850 impris… https://t.co/5qKYs7RgWr
Lawyers also alleged detainees were unlawfully imprisoned, after Papua New Guinea's Supreme Court ruled the detention of asylum seekers breached the country's constitution.
UN High Commissioner for Refugees Filippo Grandi said in a statement last month that Australia's policy of offshore processing in Papua New Guinea and Nauru had caused "extensive, avoidable suffering for far too long".
More than 2,000 people were still "languishing in unacceptable circumstances", Grandi said.