The UN says the deadly violence on Manus Island has thrown the spotlight on a wider problem with Australia's asylum-seeker policy.
The UN's human rights office has urged Australia to reconsider its policy of shipping asylum-seekers to Papua New Guinea following the deadly riot on Manus Island.
Ravina Shamdasani, spokeswoman for the UN high commissioner for human rights, said on Friday that this week's violence at the island's detention centre had thrown the spotlight on a wider problem.
"We stress the obligation of Australia, PNG and Nauru to ensure that the human rights of asylum seekers are protected in accordance with international standards," Shamdasani told reporters.
"The practice of detaining migrants and asylum-seekers arriving by boat on a mandatory, prolonged and potentially indefinite basis, without individual assessment, is inherently arbitrary. Moreover, alternatives to immigration detention should always be considered," she added.
An estimated 1340 asylum-seekers are currently being held at Manus Island.
Tensions with locals have reportedly spiked, and the detainees recently learned that if their asylum claims were approved they would only be allowed to settle in Papua New Guinea, not Australia.
Thirty-five asylum-seekers broke out of the facility on Sunday and several were injured.
In more rioting the following night, one person was killed and 77 injured, 13 of them seriously.
"While the precise circumstances are not yet clear, it is alarming to see violence against the very individuals who seek protection," said Shamdasani, adding that the incident underscored the need for independent monitoring of the facilities.
While welcoming a probe by Australian and Papuan New Guinean authorities, she said it must examine reports that private security forces were involved in the violence.
"We stress that states maintain their human rights obligations when they privatise delivery of services such as security, and must take steps to investigate, redress and punish human rights abuses by third parties," she said.