In broken English, Faysal Ishak Ahmed filled out a complaint form, demanding to know why more than 20 visits to the centre's clinic had not produced a diagnosis of his ailments, let alone a treatment plan.

For six months he had been complaining of chest pains, swollen arms and fingers, breathing problems, high blood pressure and a "problem at the back of my head".

"One thing I want to know about my healthy [sic] is are you guys able to treat me or if no tell me in write [written] form," he asked.

"I have chest, heart, high pressure and also nose block. I have problem in never of back of my head you guys have all my text there with you don't wait treating me."

A week later, Mr Ahmed visited the detention centre medical clinic with a final, desperate plea for help. He returned to his compound to tell friends the doctor had told him there was nothing wrong with him and not to come back.

Three days later, a brief media release from the Department of Immigration and Border Protection announced that a 27-year-old Sudanese refugee "has sadly died today from injuries suffered after a fall and seizure at the Manus Regional Processing Centre".

The man had been taken to the medical clinic run by International Health and Medical Services (IHMS) for urgent treatment before being airlifted to Australia and dying at the Royal Brisbane and Women's Hospital, the statement said. "The Department is not aware of any suspicious circumstances surrounding the death."

Now, Mr Ahmed's sense of frustration and despair is being felt by the almost 900 men who remain at the detention centre, some nine months after Papua New Guinea's highest court declared it unconstitutional.

Complaint made by Faysal Ishak Photo: supplied document

One of them, Aziz Adam, 24, can report that it is also consuming Mr Ahmed's parents in Sudan.

"They are really shocked and devastated. They don't even know whether they will accept this because their son left home and he was alive and now they are telling them he is dead," Mr Adam, also from Sudan, told Fairfax Media after speaking by phone with Mr Ahmed's parents.

Mr Adam says the detainees received no word on Mr Ahmed's condition after he was taken to an isolation area last Wednesday after 60 Sudanese refugees wrote a letter demanding he receive urgent treatment.

He told Mr Ahmed's parents he could not say what caused his friend's death, but that he had been suffering for six months.

"I feel there is real negligence going on in the IHMS clinic. It's one or the other. Either they are not honest with themselves about the treatment they provided to Faysal or they are hiding something."

Australian government officials have said there will be no comment beyond Saturday's short statement, which noted that the death would be reported to the Queensland coroner.

Fairfax Media put several questions to the department on Monday, including whether it was true that Mr Ahmed had seen a doctor last Wednesday and been told there was nothing wrong with him.

"As our statement says, we will be making no further comment," came the reply.

Greens leader Richard Di Natale says this is not good enough and that the Greens will press for an independent inquiry when Parliament resumes in February.

"This completely preventable death is the latest symbol of the cruelty, inhumanity and heartlessness of these camps," Senator Di Natale said.

"Faysal Ishak Ahmed wanted nothing more than our protection, and instead the government took his hope and then his life."

Labor's immigration spokesman Shayne Neumann said the death could be examined by a Senate inquiry into serious allegations of abuse, self-harm and neglect of asylum seekers in off-shore processing centres.

Dr Barri Phatarfod, president of Doctors for Refugees, said Mr Ahmed's symptoms would have warranted an urgent investigation had he been in Australia.

"In Australia, after the requisite brain scans such as CT and MRI, he would normally have cardiac investigations, such as an echocardiogram," Dr Phatarfod said.

Dr Phatarfod said there appeared to be a culture of cynicism among at least some of the IHMS health professionals.

"We have seen instances where basic tests have not been performed on people in offshore detention, and in the medical records the doctor has justified this by stating 'they often exaggerate their symptoms to get attention'," she said.

Mr Adam said the detainees were struggling to cope with the death of a young man who was "a really a good friend of everyone, not just his community".

He described Mr Ahmed as an "open person and a good person" who kept engaging with others, partly to distract himself from his deteriorating health.

"We just want to let people know what happened to this guy. He left us and he was alive."