Bangkok: The United Nations' human rights chief has lashed out at the Turnbull government, expressing "serious concerns" over the welfare, safety and well-being of more than 600 refugees and asylum seekers on Manus Island.

In a blunt statement issued in Geneva, Zeid Raad al-Hussein, the UN High Commissioner for Human Rights, described the situation on the Papua New Guinea island as an "unfolding humanitarian emergency".

Refugees and asylum seekers protesting inside the now-closed regional processing facility on Manus Island, which they refuse to leave.

"All migrants, including refugees and asylum seekers are human beings," Prince Zeid said through a spokesman.

"Like all of us, they have a right to a safe and secure environment, a right to an adequate standard of living and to participate in the decision-making process that is affecting their future," the spokesman said.