The office of the United Nations High Commissioner for Human Rights is calling on Australia and Nauru to quickly end the immigration detention of children.
This follows the release of more than 2000 leaked documents outlining allegations of assault and cruelty at the Australian offshore detention centre on Nauru, encompassing cases of sexual assault of detainees, including children.
The UN refugee agency said it was extremely concerned about the serious allegations of violence, sexual assault, degrading treatment and self-harm in incident reports from the Nauru centre, many of which reportedly involved children.
Many of the migrants, asylum seekers and refugees in these centres were transferred by Australia to Nauru more than three years ago and have been living in very difficult conditions ever since.
The UN body also urged Nauru, as a party to the Optional Protocol on the UN Convention against Torture, to establish a national mechanism for the prevention of torture and again offered to assist in this regard.
UNHRC's teams have conducted regular visits to Nauru in recent years and many of the allegations contained in the documents were consistent with the findings from these visits, a UNHCR spokesperson said.
Ravina Shamdasani said the UNHCR had regularly and persistently brought these allegations to the attention of the governments of Nauru and Australia.
It was not clear to what extent the alleged incidents were properly investigated either by the companies contracted by Australia to run the regional processing centre or by Nauru police.
She said teams from the UN office had witnessed many of the migrants, asylum seekers and refugees in Nauru, including children, suffering from severe mental health problems as a result of their detention and lack of certainty.
She said some had already experienced trauma in their home countries and sometimes also during their journey to Australia.
They were then transferred to Nauru, where they were initially detained at the regional processing centre in harsh conditions.
The UN refugee agency said over the years, and despite the opening up of the centres in October 2015, their situation had become increasingly dire and untenable, exacerbated by the indefinite nature of their time in Nauru, or for that matter at the Manus centre in Papua New Guinea.
The allegations contained in the documents must be systematically and properly investigated and those responsible held accountable.
Ravina Shamdasani said the UN body had consistently called on the authorities in Nauru and Australia to put an end to the model of processing and keeping migrants offshore.