Police on Manus Island say a refugee has died in a "very unfortunate" apparent suicide.

The Rohingya man was travelling from refugee accommodation into the island's main town shortly after 11:00am when he died.

Manus province police commander David Yapu said the man's body had been taken to the local hospital and officers were speaking to other refugees who witnessed the "very unfortunate situation".

"My condolences to his immediate family," Mr Yapu said.

"This is something that we were all caught by surprise."

The man is the seventh asylum seeker sent to Manus Island by Australia who has died.

The last three of those deaths — all of which have occurred in the past 12 months — have been apparent suicides.

The Asylum Seeker Resource Centre said the latest death showed the impact of offshore detention on the men's mental health.

"This tragedy reinforces the cruelty of holding men, women and children offshore," said Jana Favero, the ASRC's director of advocacy.

"This is a catastrophic policy failure that has taken yet another life."

Papua New Guinea's Immigration service said it was still trying to confirm details of the man's death.

The United Nations Refugee Agency's deputy regional representative in Canberra, Nai Jit Lam, said the agency's thoughts and condolences were with the man's family.

"With the passage of too many years and the withdrawal or reduction of essential services, the already critical situation for refugees most in need continues to deteriorate," Mr Lam said.

"Australia's responsibility for those who have sought its protection remains unchanged."

Greens senator Nick McKim blamed both Labor and the Liberals for the death.

"This man sought Australia's help and suffered years of deprivation for daring to ask," he said.

"His death is a direct result of political decisions of the Labor and Liberal parties.

"He faced the impossible choice of indefinite detention or returning to face ethnic cleansing in Myanmar."

Senator McKim called for the detainees on Manus Island and Nauru to be brought to Australia.

Australia's Department of Home Affairs confirmed the death.

"The Department is aware of the death on Manus Island," it said in a statement. "Further enquiries should be referred to PNG authorities."