Australian immigration detention facilities comprise a number of different facilities throughout Australia, including the Australian territory of Christmas Island. Such facilities also exist in Papua New Guinea and Nauru, namely the Nauru Regional Processing Centre and the Manus Regional Processing Centre. They are currently used to detain people who are under Australia's policy of mandatory immigration detention. Asylum seekers detected in boats in Australian waters have been detained in facilities on the offshore islands of Nauru and Manus Island, previously under the now defunct Pacific Solution and (since 2013 and ) under Operation Sovereign Borders. The facilities' existence is controversial and has been condemned on human rights grounds and have even been likened to concentration camps by some critics and human rights groups. The United Nations High Commissioner for Refugees (UNHCR) has cited these centres as a "damning indictment of a policy meant to avoid Australia's international obligations". Background The Migration Act 1958 allowed discretionary detention of unauthorised arrivals until 1992. Since the 1990s when the Keating Government created a policy of mandatory detention of unauthorised arrivals, with non-citizens arriving by boat without a valid visa being detained until they were either granted a visa, or deported. Towards the end of the 1990s, a large increase in the number of unauthorised arrivals exceeded the capacity of the existing Immigration Reception and Processing Centres (IRPCs) at Port Hedland and Curtin. Facilities Immigration Detention Centres (IDCs) Immigration detention centres detain people who have overstayed their visa, breached their visa conditions and had their visa cancelled or have been refused entry at Australia's entry ports. This includes irregular maritime arrivals claiming asylum without passports, identity papers or valid entry visas. Under the Migration Act 1958, people arriving in this manner are classed as unlawful non-citizens and are currently subject to mandatory detention. However, in 1954 the Australian government ratified the United Nations Convention Relating to the Status of Refugees. Under Article 31 of the convention, the Australian government is legally obligated to grant anyone fleeing persecution and seeking asylum the right to enter the country by whatever means possible. Furthermore, the Article states that signatory countries are not to impose penalties on or indefinitely restrict the freedom of movement of those seeking asylum. Australia's Migration Act 1958 requires people who are not Australian citizens and who are unlawfully in Australia to be detained. Unless they are given legal permission to remain in Australia