GENEVA/SYDNEY - A UN committee found that Australia violated a human rights treaty by detaining a group of asylum seekers, including minors, on the remote Pacific island of Nauru even after they were granted refugee status, it said in a statement on Thursday.

Under Australia's tough immigration policies, those attempting to reach the country by boat have been sent to detention centers - including on the South Pacific island nation of Nauru - for so-called "offshore processing" since 2013. Such facilities have previously drawn scrutiny from rights groups.

The UN Human Rights Committee, which monitors the legally-binding 1966 International Covenant on Civil and Political Rights and was asked to consider a complaint by a group of refugees, found that Australia had violated two provisions of the treaty: one on arbitrary detention and one protecting the right to challenge their detention in court.

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It asked Australia to provide compensation to the victims and to ensure similar violations do not recur.

"The outsourcing of operations does not absolve States of accountability," said Committee member Mahjoub El Haiba. "Offshore detention facilities are not human-rights free zones for the State party, which remains bound by the provisions of the Covenant."

A spokesperson for Australia's Department of Home Affairs said in a statement it was engaging with the UN on the complaints.

"It has been the Australian Government’s consistent position that Australia does not exercise effective control over regional processing centers," the statement said.

"We welcome Nauru’s continued partnership in the effective delivery of regional processing arrangements."

The office of Nauru Prime Minister David Adeang did not respond to a request for comment.

Australia's policy of detaining asylum seekers offshore is popular with voters. Its government says they are treated with dignity, fairness and respect and given access to a range of support services.

The UN committee finding follows a 2016 petition filed with it by a group of 24 asylum seekers from Iraq, Iran, Afghanistan, Pakistan, Sri Lanka and Myanmar who were intercepted while trying to reach Australia by boat in 2013, when they were aged between 14-17 years old.

The group, who were unaccompanied and transferred to Nauru from Christmas Island in 2014, were held in the overcrowded Regional Processing Centre where they lacked access to sufficient water and healthcare, the UN statement said.

Nearly all the minors suffered a deterioration in well-being there, including weight loss, self-harm, kidney problems and insomnia, it said.

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They remained in detention in Nauru even after all but one of the group were granted refugee status, the statement said. It did not specify the total duration of their detention nor did it give information on their identity or current whereabouts.

Australia argued that there was no proof that the alleged violations had occurred within its jurisdiction, according to the UN statement. However, the committee found that the Nauru facility counts as being within Australia's jurisdiction, citing the country's role in constructing and financing it.

In a second case filed to the same committee, it found that an Iranian refugee who had been held in Nauru had also been subject to arbitrary detention, the statement said.