Resolve the fate of detainees, Labor to PM

Labor has called on Prime Minister Malcolm Turnbull to resolve the fate of detainees on Nauru and Manus Island after a second set themselves alight.

Labor says there are problems with how the government is managing its offshore processing program. (AAP)

Labor believes there is something wrong with how the government is managing its offshore processing program after a second refugee on Nauru set herself on fire.

The opposition's immigration spokesman Richard Marles believes the focus on deterrence with no pathway to permanent migration in a resettlement country is leaving people desperate and without hope.

Prime Minister Malcolm Turnbull "must urgently seek a viable agreement to resolve the fate of people on Manus Island and Nauru," he said on Tuesday.

The UN refugee agency says the existing policy of offshore processing and prolonged detention is immensely harmful.

"Despite efforts by the governments of Papua New Guinea and Nauru, arrangements in both countries have proved completely untenable," the UNHCR said in a statement.

"UNHCR's principal concern today is that these refugees and asylum seekers are immediately moved to humane conditions with adequate support and services."