An Australia-based refugee advocate says the International Organisation of Migration, or IOM, has visited jailed asylum seekers on Papua New Guinea's Manus Island.
The IOM ran the asylum seeker centres on Nauru and Manus Island during the Howard Government.
The Refugee Action Coalition says the IOM is asking asylum seekers to agree to voluntarily return to their home countries.
The group's spokesperson, Ian Rintoul, says that is despicable and the IOM is taking advantage of asylum seekers who have been abused and are being held unlawfully in jail.
Mr Rintoul says there is an urgent need for human rights observers on Manus Island - at the detention centre and in the jail.