The government adviser who recommended re-starting offshore processing in Nauru and Manus Island has urged ministers to abandon the policy and bring refugees to Australia before more kill themselves.

Paris Aristotle, who has advised successive governments on refugee policy, said if refugees were left on the two islands it was “highly likely that many more men and women will express their despair by attempting to harm and kill themselves”.

Aristotle, the executive director of the Victorian foundation for survivors of torture, said: “We also hold grave concerns that children and young people in Nauru will respond in the same ways,” adding that neither PNG nor Nauru could offer refugees a safe long-term future.

“Improving conditions and services in PNG and Nauru will not prevent this [continuation of self-harm].

“An effective and sustainable response must involve the option of resettlement in countries including Australia which offer the opportunity for refugees to become integral members of society, to live in security and to participate in the economic, social and cultural life of their new homes.”

Aristotle, along with Michael L’Estrange, Sir Angus Houston, sat on the 2012 Expert Panel on Asylum Seekers, that recommended to the Gillard Labor government, along with 21 other recommendations, the re-opening of offshore detention camps on Nauru and Manus as part of “comprehensive regional network”.

However, many of the report’s other key recommendations designed to complement offshore processing have not been implemented – including those to lift Australia’s humanitarian intake to 27,000 (currently 13,750), and to pursue stronger co-operative agreements with countries such as Malaysia and Indonesia.

In his current statement, Aristotle argued that the old defence of offshore processing – that it served as a deterrent to irregular boat journeys to Australia and thereby saved lives at sea in Australian waters – was no longer valid.

“Australia, Indonesia and other nations have increased their capacity to respond to irregular migration,” he said.

“To ensure this can be sustainable we must also build a regional system based on established human rights principles, which aims to ensure that asylum seekers are protected properly in countries of first asylum or transit, are processed fairly, and, for those found to be refugees, are afforded timely settlement outcomes.”

However, Aristotle said, before a long-term regional resettlement framework could be established, the current abuses

“The immediate imperative is that Australia acts swiftly to change the present policy settings that are inflicting serious harm.”

Australia’s offshore processing camps on PNG’s Manus Island and Nauru have come under sustained pressure almost since they were re-opened in 2012 over systemic abuses, violence (including the murder by guards of one asylum seeker, Reza Barati), sexual assault of women and children, and catastrophic rates mental illness, self-harm and suicide attempts.

In April, Iranian refugee Omid Masoumali publicly doused himself in petrol and set himself alight on Nauru in protest at conditions. After critical delays in care and in moving him to a hospital off the island, he died in Brisbane.

The camps have been condemned as illegal, arbitrary and indefinite detention by numerous arms of the United Nations, dozens of other national governments, and the Australian Human Rights Commission.

Pressure has been particularly acute since the publication by The Guardian last month of The Nauru Files - more than 2000 leaked incident reports from that island that detailed systemic abuses, sexual violence against women and children, almost-daily reports of self-harm, and a culture of impunity for perpetrators of abuse.

The overwhelming majority of those forcibly sent to Nauru and Manus have been found to be refugees, that is, they have a “well-founded fear of persecution”, are legally owed protection, and cannot be returned to their homeland.

Of the men on Manus who have had their asylum claims assessed, 98% have been found to be refugees. On Nauru, that figure is 77%.

The Guardian has approached the department of immigration and border protection for comment.