Amnesty International is describing new laws in Nauru restricting medical transfers off the island a "dangerous and callous act."
Nauru rushed through regulations on Friday which will block medical referrals made by overseas doctors, including via online services.
Amnesty International's Director of Global Thematic Issues, Meghna Abraham said the new laws could have deadly consequences for refugees on Nauru.
Ms Abraham said it showed how far the human rights of refugees have slipped down Nauru's agenda.