GENEVA (Reuters) - Australia should stop rejecting refugees and change its migration laws to come into line with international standards, the U.N. Human Rights Committee said in a report on Thursday. The committee, which comprises 18 independent experts and monitors countries  compliance with a global human rights treaty, said Australia should come back in a year to explain what action it had taken to meet its concerns. Australia has been widely criticized by the United Nations and rights groups for detaining asylum seekers who try to reach its shores by boat, even if they are found to be refugees, and keeping them on offshore processing centers in Nauru and Papua New Guinea. The United Nations has warned of a  looming humanitarian crisis  in the Manus island center in Papua New Guinea. It was closed on Oct. 31 but 600 asylum seekers have refused to leave, fearing violent reprisals from islanders if they move to transit centers, pending possible resettlement to the United States. The committee s vice-chair Yuval Shany said although the recommendations were non-binding it did not appear Australia was treating its obligations seriously.  We do not disagree with Australia s right to adopt a tough policy, for instance on resettlement,  he said.  What they cannot do is treat asylum seekers as criminals and detain them, and they cannot absolve themselves of their duty not to send them back to danger.  He said it was exceptional to have such a situation in a developed country with a strong human rights record, and for a country to publicly reject the committee s recommendations one after the other, as Australia had.  The government could not be immediately reached for comment. Immigration Minister Peter Dutton earlier told 2GB radio he stood by the detention policy that the government says is necessary to deter asylum seekers from attempting perilous sea voyages to Australia, and that it would not back down from its evictions from Manus. The offshore detention policies are backed by the center-right government and the Labor opposition.  The U.N. committee said Australia should cut the period of initial mandatory detention and limit detention overall, and ensure that children were not detained except as a measure of last resort and for the shortest time possible. It urged Australia to ensure the international principle of not sending refugees back to danger was secured in law and adhered to.  The committee was concerned about conditions in Manus and in Nauru, citing serious safety concerns and instances of assault, sexual abuse, self-harm and suspicious deaths. Australia should also consider closing the Christmas Island detention center, which was too remote to ensure protection of people held there, it said. 