Following an 18-day mission to the country, Francois Crepeau, United Nations Special Rapporteur on the human rights of migrants, told reporters in Canberra on Friday that the country's boat turnaround policy was "regressive and falls way behind international standards."

After visiting asylum seeker detention facilities in Nauru, Crepeau noted that the conditions asylum seekers faced in detention "amount to cruel, inhuman and degrading treatment."

Australia has a stiff border policy of intercepting and turning back all boats carrying asylum seekers. 

Canberra also sends asylum-seekers trying to reach Australia by sea to isolated outposts on Nauru and Papua New Guinea's Manus Island.

The government has defended its position, including turning boats back, as necessary to stem waves of migration by people from war-torn Afghanistan, Sri Lanka and the Middle East.

"It is a fundamental principle of human rights law that one person cannot be punished only for the reason of deterring another," Crepeau said, while also praising Australia for increasing its refugee intake and welcoming Syrian refugees.

Canberra this month announced a "one-off" deal to settle an unspecified number of the 1,600 persons held at Nauru and Manus Island in the US.

Prime Minister Malcolm Turnbull last week said that the US had agreed to resettle those held in detention, but did not give a timeline or the number of people.

There is also concern the agreement could be scrapped after the election of Donald Trump, who campaigned to ban Muslim immigration.

jbh/kl (dpa, AFP)