The spokesperson said Nauru has jurisdiction over the regional processing arrangements and the detention centres come under Nauru’s international law obligations.

“Offshore detention facilities are not human-rights free zones for the state party, which remains bound by the provisions of the Covenant.”

Australia’s treatment of refugees has been criticised in the past. Credit: AAP

The finding follows a 2016 petition filed with the UN committee 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 and 17 years old.

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

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.