Australia broke global human rights rules by denying a group of refugees from Sri Lanka, Myanmar and Kuwait a chance to challenge their detention imposed on security grounds, a UN watchdog said Thursday.
The criticism from the UN Human Rights Committee comes as campaigning for Australia's 7 September elections puts the long-running issue of "boat people" centre stage.
"Australia's indefinite detention of 46 recognised refugees on security grounds amounted to cruel, inhuman and degrading treatment, inflicting serious psychological harm on them," the UN committee said in a statement.
In a review of complaints from the refugees — 42 Sri Lankan Tamils, three Rohingya Muslims from Myanmar and a Kuwaiti — the committee said the detention was arbitrary and broke the International Covenant on Civil and Political Rights.
The plaintiffs arrived at Australia's remote Christmas Island between March 2009 and December 2010.
Despite being recognised as refugees who could not be sent home, the plaintiffs were kept in immigration detention centres on Christmas Island and mainland Australia because the Australian Security Intelligence Organisation deemed them potential threats who should be denied a visa.
They filed their UN complaints in 2011 and 2012. Since then, seven have been granted Australian visas and freed.
The committee said that Australia must release all 46, grant them access to justice, and offer compensation.
"The committee reached its conclusion based principally on the fact that the refugees were not told the reasons for the negative security assessment and so were unable to mount a legal challenge to their indefinite detention," the UN body said.
While Australia told the committee that releasing classified details would compromise the assessment system and national security, it nonetheless explained that they posed one or more of three specific risks.
These were the threat of fomenting violence in Australia, providing a save haven for organisations to prepare attacks against their homeland's government, and of raising funds in Australia for foreign terrorists.
Though they come in relatively small numbers by global standards and are outpaced by legal migrants, refugees and other boat people are a sensitive political issue in Australia and have featured prominently in election races since 2001.
Labour Party Prime Minister Kevin Rudd, who is trailing conservative Tony Abbott in the opinion polls, has gambled his fortunes on a plan to send boat people to impoverished Papua New Guinea for processing and resettlement.
That has sparked criticism from rights monitors who have faulted Australia in the past for "offshoring" rights obligations under governments of various political stripes.
Abbott has pledged his own crackdown, with all refugees put on three-year temporary visas and forced into a work-for-welfare programme without rights to family reunion, appeal or permanent residency.